Support Section

Nu-Bird Suction Mirrors are the ultimate essential instrument that today’s dentists, hygienists and assistants are using in office for suction, viewing and retraction.

FAQs

Got a question? We’re here to help.
  • Nu-bird Special Design Features

    Slim, angled like a dental mirror- lightweight, high port velocity, ergonomic, swivel feature makes it easy to navigate the mouth following the aerosol geneerating tip. It also works well for strong retraction with clear indirect vision so you don't have to stop to pick up your mouth mirror to view an area you just went over. 

  • Think mirror holes are too small to be HVE?

    We have performed scientific timed water tests to demonstrate high volume capacity. We have measured Cubic feet per minute (CFM) in airflow volume of our Mirror head along side a standard HVE tip speed and CFM volume and they are virtually the same speed.  This was done with our Mirror directly plugged into and HVE valve. Note*** When our mirror is used with an added ergonomic hose, the speed is about 2 seconds slower due to the extra 5 feet of  hose length the water has to travel through.  A small trade off for easier ergonomics. The wide hole pattern footprint on the mirror head offers a wider air path likened to a "Catchers mitt" which better captures aerosols. 

  • Isn't HVE supposed to be "Big Bore"?

    The bigger the bore, the lower the "pick up' power

    or "Velocity" which could increase the chance of  regurgitation in some offices. YOU NEED BOTH HIGH VOLUME AND HIGH VELOCITY.

  • HOW DO I CHANGE THE MIRROR FACE WHEN IT BECOMES SCRATCHED?

    The mirror face coin can be easily removed with a special Key which when inserted in the mirror handle end, enables the scratched coin to lift out of the mirror head. A new mirror coin can then be easily snapped into place. See our video demonstration called ”Replacing the Mirror face.” on our website or review our USER GUIDE listed under the Support Tab.

  • HOW DO I KEEP WATER FROM BEADING UP ON THE MIRROR FACE?

    This happens due to a residue coating left from the manufacturing of the new mirror coin, lip products which can smear on the mirror from patient’s mouths and also from residues which come from sterilization when the mirror has not been cleaned and rinsed adequately. Removing these residues is the most important routine step. 


    Wiping mirror face with alcohol is needed to clear residues off the surface. Using Nu-bird Mirror clearing granules by sprinkling onto a wet mirror face creates a surfactant which helps to break up the water surface tension. This keeps the water from beading and provides clear viewing through an entire procedure. 

  • WHAT SHOULD I DO IF MY PATIENT HAS A TENDENCY TO CHOKE AND GAG EASILY?

    We recommend adding an additional saliva ejector angled to rest in the back of the mouth between the tongue and retro-molar pad to help prevent choking and gagging from any excess water that makes its way to the back of the mouth. 


    We also recommend telling your patient not to breathe though their mouth when you are using ultrasonic devices because they may aspirate vapor aerosols which can cause them to choke or cough.

  • Our Vision for the design of Nubird Mirror system

    We invisioned every possible secenario hygienists needed to fulfill the list of demands and wanted to create an absolute dream instrument to use to help make their work load easier, more ergonomic with better time management.


  • What is the difference between the Stainless steel mirror and the Silver Raven mirror?

    Two main differences:  The Stainless model is built using surgical stainless steel which is industrial and designed to last a career and has lifetime warranty against mfg.defects. The Raven mirror is our light weight series which is easier and lower cost to manufacture. Not as labor intensive as the stainless model. This model  has a long life as well but designed more for hygienists to use with ultrasonic units and who require the ultra lightweight for  ergonomics. Dental burs could  scratch finish more easily than the stainless model if used by dentists for restorative procedures. 

  • CAN THE NU-BIRD SUCTION MIRROR PLUG INTO THE HVE EVACUATION LEVER?

    Our Nu-bird DC direct connect mirror is versatile and plugs directly into the high volume suction evacuator port. Perfect for chair side assisting. We now have a new "Heron DC" model which now has  a swivel feature making it much more ergonomic to use with standard HVE valve. 

    For practicioners who work alone, we recommend our regular HVE mirrors, the Stainless and the Raven mirrors to be used with our Ergonomic HV hose which reduces repetetive strain on wrist and arm. 

  • Title or question
    Describe the item or answer the question so that site visitors who are interested get more information. You can emphasize this text with bullets, italics or bold, and add links.

Suction Mirror User Tips

Please Read before using your new mirror.
When developing the new skill of using HVE, Retraction, Indirect viewing with Ultrasonic scaling and air polishing procedures, it is important to allow time and repetition to train both hands to work simultaneously. This is a brand new advanced skill where one is managing three-four tasks at once. Start by following these simple steps.

STEP 1:

PROPER SET UP
Plug the 9.5mm bore metal curved end adapter into HVE.
Loop hose as shown and affix Ergo Clip onto top of curved metal hose end adapter (The excess hose is lifted in an upward position allowing it to fountain and reduce drag and pull on the wrist and arm)
Point curved metal adapter and hose toward patient’s head. Adjust hose tubing to an ergonomic working length.

POINT HOOK AND HOSE
TOWARD PATIENT’S HEAD
Insert Nu-bird Mirror into other end of Hose Adapter until it “Clicks in” and freely rotates without falling out.

STEP 2:

MIRROR PREP -
ALWAYS BE SURE TO PREP THE MIRROR FACE
VERY IMPORTANT!
If water beads on the mirror face there are residues present which have to be removed.
Water commonly tends to bead-up on the surface of the mirror inhibiting clear viewing capability due to residues present on the mirror face. 

To solve this problem simply wet mirror lens, sprinkle lightly some dry Knox gelatin on the reflective surface. With gloved finger, swirl in circular motion, wait couple seconds for granules to dissolve, mist off with light air water spray and GO!!
This technique works efficiently as a surfactant allowing the mirror to remain clear without obstruction of view. When water beads on the mirror surface, it is because there are residues present associated from sterilization, patient lip products, and oils from water spray in the lines of high speed handpieces. It is very important to make sure the mirror is rinsed well after ultrasonic bath and gently wiped before placing in autoclave bag for sterilization.

Before Prep: Beaded Water 
After Prep: Water Spreads Out
It is also recommended to wet the mirror with a good biofilm/saliva coating from patient’s buccal mucosa and under tongue. Use as a retractor, then suction and lastly as a mirror. 

STEP 3:

ULTRASONIC TIP SELECTION AND SETTINGS
It is very important to determine and use the correct insert for the level of deposit removal. Place ultrasonic insert into the handpiece adjust to correct power and water volume levels. Water should “aerosol” and drip, not stream."

STEP 4:

Determine whether the cause is Tissue or Tooth.
ALWAYS ASK PATIENT IF THEY HAVE SENSITIVITY ON THEIR TEETH OR GUMS PRIOR TO THE START
OF PROCEDURE.
For Tooth Sensitivity due to erosion, recession,
and abfractions; we recommend pre-polishing with NuPro Extra Care which contains Novamin. Use a soft exterior webbed prophy cup to burnish polish into root surface. Polish buccals first then lingual, suction only do not rinse off until completed. 
This works very well in most cases.

For Tissue Sensitivity due to gingivitis or periodontal inflammation; we recommend using a periodontal anesthetic gel designed for scaling. Place around sulcus prior to procedure. Suction only do not rinse out for a couple minutes. This works very well and patients are comfortable through the whole procedure.

STEP 5:

HVE SUCTION WITH RETRACTION OF TONGUE AND CHEEK
Retract Tongue and suction with MIRROR FACE placed against the tongue using DIRECT VISION 

Turn on suction, adapt ultrasonic tip to tissue and work with both devices starting on the distal lingual of the lower second molar working slowly toward the anterior of the mouth.
Retract the Cheek and suction with the mirror face placed against mucosa using DIRECT VISION

Start on the distal buccal of the lower molars and work with both devices moving forward toward anterior teeth.
Retract the Cheek and suction with the back of mirror face still USING DIRECT VISION

Start at distal buccal of maxillary 2nd molar and use both devices to scale the linguals moving the mirror slightly back and forth aspirating the aerosolized water and any residual water in the back of the mouth.
Very Important to develop a good saliva/ biofilm coating on the mirror face which also aids in keeping mirror clear through whole procedure.

STEP 6:

YOU'RE NOW READY TO LEARN HOW TO USE INDIRECT VISION, RETRACTION,
SUCTION ALL TOGETHER WITH AN ULTRASONIC SCALING DEVICE
Place the BACK side of the Suction mirror against the buccal mucosa close to the distal of the second molar in upper arch. Use INDIRECT VISION to view adaptation of the ultrasonic tip work with both devices moving toward the anterior region of the mouth.

Walk the mirror moving it slightly back and forward collecting any residual water and manage aerosols.

Keep the mirror face wet with water spray and at the same time watch the ultrasonic tip placement working carefully toward the anterior region of the mouth.
Because dental suction systems all vary in power and performance, during this phase it can be helpful to add a saliva ejector, curved like a cane and placed in the back of the mouth to manage any residual water. This allows the clinician to focus attention and gaining skill learning to work using both hands with both devices simultaneously.
When working on anterior linguals using INDIRECT VISION, intermittently as needed “dip down” placing the back of the mirror against the tongue near the distals of the lower molars and aspirate any residual water.
When working on the anterior facials flip the mirror to retract the lips with the face of the mirror.
This will better control aerosols generated from the ultrasonic tip and help keep excess splatter off the patient's face and clinician.
Patients can comfortably close down slowly on the first ½ edge of the mirror “like a spoon” to remove residual water efficiently from the back of the throat. Because of the patented hole design, there is a constant positive air flow which prevents back flow to occur.

     CHANGING THE  MIRROR FACE

1.Insert KEY in end of handle with the 90º angled end in UPWARD position
2. Make certain the mirror face moves forward before turning the KEY Gently rotate KEY 90º to the right and left back and forth until you see the mirror face dislodge and raise up. On brand new mirrors sometimes the spring inside is a little tight so one may need to depress the mirror lens between your thumb and forefinger in a Pinching fashion on the top part of the lens, while rotating the Key to aid in dislodging the coin. 
3. The mirror face can then be removed out of mirror head by placing the opposite end of the KEY inside the center port of mirror head and nudged to slide toward handle.
The Mirror Key is fully sterilizable. Place on middle tray in Autoclave.
BE CAREFUL NOT TO USE EXCESSIVE FORCE OR JAM AND TWIST
THE KEY OR OTHER ITEMS INSIDE THE MIRROR HANDLE AS DAMAGE CAN OCCUR TO THE
INNER SPRING AND MIRROR HEAD!
4. Slide new mirror coin under tabs on head the same angle it was removed.
5. Using the dominant hand, squeeze edge mirror coin between thumb and and fore finger on the top edge of the mirror head, while using non-dominant hand/thumb to securely push forward and click into place in mirror head.

CLEANING, DISINFECTING AND STERILIZATION


Nu-bird Mirrors should be placed into automated cleaning  unit such as an ultrasonic bath, or automated washer to remove debris. It should be placed inside a plastic cassette. This will help prevent scratches on mirror face from other instruments. It can be then placed in sterilization bag and then autoclaved. 
It is not necessary to remove the mirror face coin prior to a sterilization cycle, but is fine if one desires to perform the extra step. During use, calculus and debris go through the ports and is quickly pulled from the head chamber through the larger evacuation channels leaving nothing left behind. 

Suction Mirror and or hose should be placed near the center of the autoclave away from sidewalls and bottom heating elements. Avoid layering instruments on top of mirrors or hose and over filling autoclave as overheating and damage can occur.

For a higher level of disinfection, the HVE Hose is designed to hold up under repeated autoclave cycles with longer life than traditional silicon tubing making it perfect for mobile dentistry.

If the HVE Ergonomic hose is to remain in the clinic room, It could also be treated the same as a regular HVE hose by running a disinfectant solution through it and wipe down with antiseptic wipes. Barrier bags can be used to cover the end of hose where the mirror inserts if autoclaving between patients is not an option.
STERILIZE MIRROR AT 
121ºC (250º F) 
30 Minutes Mimium
Sterilization Cycle and
Pre-vacuum Steam (dynamic)
132º/270º  4 Minutes
To keep silicone hose feeling like new, place 1 tsp. of cornstarch on a clean dry cloth or into the palm of a gloved hand and wipe down tubing. This will restore smooth texture making it easier to adjust working length. 
The curved hose end adapter which plugs into the HVE port can be removed from hose if desired. DO NOT REMOVE HOSE END FROM HOSE WHERE MIRROR PLUGS INTO AS IT WILL DAMAGE THE SPRING INSIDE.  
Note: Discoloration from baked on aseptic solution residues can occur if hose has not been properly rinsed or wiped dry prior to autoclaving.

PRODUCT MAINTENANCE

The O-Ring inside the adapter end of the hose, where the mirror connects, may be replaced when worn out. Replacement O-Rings are available from any hardware store. Measurements: ½ OD x 5/16 ID x 3/32

Sometimes with repeated flushing of the lines, the chemicals dry out the O-ring inside the adapter fitting. This O-ring will need to be lubricated monthly to moisten so the mirror slides in easier and rotates smoothly. You can use chap stick or vaseline as a lubricant.

TROUBLESHOOTING TIPS

If the mirror seems to pull out of the hose adapter when you lift it to use, it is not pushed into the adapter end far enough. You should feel it click into place and rotate easily. If it is very hard to push the mirror in to the hose end then that is a signal the O-Ring needs lubrication with vaseline or chapstick or silicone lubricant being placed on a cotton swab to lubricate the o-ring.


To keep silicone hose feeling new, place 1 tsp. cornstarch on a clean dry cloth or into the palm of a gloved hand with and wipe the tubing down. 

Attach hose end on Hose Rest Clasp allowing the hose to hang down when not in use.

TECHNIQUE, TIPS AND TRICKS

  • For best ergonomic positioning, we recommend sitting between 11:00 and 1:00 chair position. If the operatory does not allow this positioning, then turn patient’s head to the side for better access.
  • KEY: Ergonomically, the Ultrasonic unit should always be as close to the dominant hand as possible and Suction (HVE) always on non-dominant hand’s side. 
  • Place Saliva Ejector in the back of the mouth while learning to use system. It is not necessary but some offices have weak suction systems so this may helpful when developing your new skills.
  • IT is easy to retract with either side of the mirror in order to view and manage the water. Just rotate the mirror like a standard mirror to move about in the mouth. 
  • The mirror can also be flipped and angled sideways to inhale a broader amount of aerosols from both front and back sides when working on upper anteriors. This works great for air polishing.
  • Use the suction mirror instead of standard mirror to avoid fogging when hand scaling in the mouth. Also great for use during standard exams, adjusting occlusion or tough to view and access CLV fillings. 
  • Use mirror’s suction instead of saliva ejector for polishing with prophy-angle to remove excess saliva.
  • Use Suction Mirror instead of HVE for sealant placement, air polishing and laser procedures.
IN MOUTH SUCTION MIRROR PLACEMENT
Patients can comfortably close down slowly on the first ½ edge of the mirror "like a spoon" to remove any residual water in the back of the throat.
There is no concern of backflow due to the patented hole design. There remains a constant and continuous HV air flow making backflow impossible. 

PATIENTS WHO TEND TO GAG EASILY WITH ULTRASONICS
Simply add an additional saliva ejector bent at an angle to fit in the posterior corners of the mouth. This helps to remove additional moisture from aerosols with the water spray. 

ASPIRATE WATER MIST MAY CAUSE CHOKING
Be sure to tell the patient not to breathe through their mouth. Breathing through their mouth may aspirate water mist which can cause choking or coughing

PERFECTED AND DEVELOP NEW SKILLS
Learning to use both hands simultaneously when working in the mouth is a brand new skill. Success with this system highly depends on the clinician’s spatial skill level and the ability to use high volume suction with indirect vision and retraction.

AVOID LEAVING THE SUCTION MIRROR IN THE SAME POSITION FOR LONG PERIODS OF TIME
In rare circumstances, elderly patients or those with xerostomia, the buccal mucosa can dry out and may get stuck to the front or back side of the suction mirror. This happens because the suction mirror has been left in the same position for a long period of time. The HV suction is very powerful, adjust the lever on the HV to a lower level if needed to reduce suction power.


USE STANDARD HVE TIP WITH NU-BIRD HOSE

To use Nu-Bird hose with standard HVE tip, simply insert the Nu-Bird swivel HVE connector fitting into the gray hose end fitting until it clicks and rotates freely, then insert HVE tip into connector port. Use the modified pen grasp to hold HVE and rotate between fingers for better angulation.
Standard HVE System 
*Notice how the HVE is held with hand, which causes fatigue and leads to poss. RSI
Nu-Bird HV Ergonomic Adapter
Allows free rotation and is held with modified pen grasp. Better control of aerosols and ergonomics.

Nu-Bird Mirror System Products

Silver Raven Mirror

The Silver Raven series of Nu-bird Mirror is feather light and weighs just 13 grams. This model is stronger, quieter, high in air velocity and the mirror face is replaceable when worn.
This one has it all! 

Stainless Steel Mirror

The Nu-Bird Suction Mirror provides high volume suction with strong retraction with clear fog free view to those hard to see areas in the mouth. Designed for longevity and also more cost efficient to use.

Silicone HV
Adapter Hose

This high grade silicone adapter hose offers a swivel feature on the end where the mirror plugs into which allows the mirror to rotate effortlessly when moving about in the mouth thus making it very ergonomic to use. The curved hose adapter end easily plugs into HV evacuator port. The U- shape design prevents the hose from crimping. 
BUY NOW

Ergonomic Design

Balanced lightweight design reduces strain on arm and wrist. It’s not only form, function and beauty all-in-one.

Independent dental practitioners are pioneers in the forefront promoting access to care for those who would otherwise have no access. The Nu-Bird, formerly known as Hammer Head, High volume Suction mirror provides a means to provide comfortable treatment for both patient and provider. 

Our superior designed Nu-Bird Suction Mirror offers a balanced lightweight design which makes it ergonomic to hold thus reducing strain on arm and wrist. It’s not only functional, but looks cool too! 
The Nu-Bird Suction Mirror, formally Hammer Head”, is the ultimate suction/viewing/retraction instrument for dentists, hygienists and assistants. It combines two essential pieces of equipment, mouth mirror and high volume suction, into one easy to use device.

Suction holes are on the front and back of the mirror. The holes on the front are in direct con­tact with the reflective surface and are what keeps the water and debris off the mirror and out of the way for clear fog free viewing. The holes on the back won’t plug with tissue and bog down lessening the suction power of the HVE.

The strong suction capacity is the level of a straight high vacuum tip which efficiently captures the aerosols and water debris. Patients love this mirror because of its efficacy in thorough evacuation of the water keeping them from feeling like they are drowning when clinicians use the ultrasonic or other HV water spray.

The Nu-Bird design deflects oral tissue away from the suction ports making it perfect for simultaneous retraction and suction. The mirror works efficiently in keeping the cheek or tongue out of the way. The suction ports won’t harm soft tissue like other suction devices because of its patented hole design. This mirror can fully adapt to both high and low suction delivery systems.

Clinically tested since 2008 in the following adverse conditions: Thick cheeks, large thick tongues, small mouth opening, see the distal of third molars, blood and saliva flow and all special needs patients.

This mirror outperforms all other similar devices, making it the perfect companion for use during ultrasonic scaling procedures, sealants, class V fillings, water-laser therapy and air polishing.
The mirror weighs 17 grams (about the same as a 4r4L instrument) and feels very lightweight.

We have added a HVE ergonomic Hose Adapter which is sterilizable and has a swivel feature that allows the mirror to rotate effortlessly when moving about in the mouth. The hose is lightweight, flexible and made of very high-grade silicone which can be autoclaved repeatedly. This accessory helps you can get the most from your new device.
Proudly Made in the USA

This mirror saves valuable time, money and allows clear indirect viewing thus raises the bar in the standard of care being provided.

Specifications:
The mirror head is 1 inch in diameter by .23 inch thick. The handle is 6 inches long overall and 3/8 inch at its thickest and .25 at its thinnest. The mirror head holds a #3 High Definition mirror face lens is which is the same size as the old standard #4 dental mirror.
Features and Benefits
• Clear view while ultrasonic scaling difficult to access areas 
• Efficiently removes pooling liquid on the mirror face and in the mouth
• SRP time cut in half
• Accurately place sealants in 1/3rd the time over traditional methods
• Perfect companion for water laser therapy
• Saves chair time and extra appointments with increased production
• Strong and steady retraction device for thick tongues, cheeks and difficult patients
• Design deflects oral tissue away from plugging suction ports maintaining suction level
• Replaceable #3 high definition mirror lens offering brighter visibility 
• Adapter hose allows free rotation, ergonomic design eliminates body fatigue
• Easily adapts to High or Low volume suction systems.
• Scientifically proven to reduce aerosols better than traditional methods 
• High volume suction performance level offering wider air pathway for better aerosol capture
• Long life, eco-friendly, fully sterilizable
• Patient comfort. 

When trying other similar devices on the market, don’t settle for an imitation.
Quantity is not a substitute for performance. 
Our patented design is guaranteed to outperform all others in its class.

Adaptability

The Nu-Bird Suction Mirror is all-in-one ultimate high volume suction, viewing and retraction instrument that is both ergonomic, portable while offering mobility. It can go wherever you go - like having a personal assistant.
PICK ONE UP, PLUG IT IN AND GO!
So you can take it with you to most all types of clinic settings whether it is a dental office, mobile care unit, or onsite nursing facility. When using a Nu-Bird SM you can enjoy easier access on tough patents, clearer viewing and improved ergonomic positioning while performing dental cleanings and restorative procedures.
MIRROR PROVIDES COMFORTABLE HANDLING
This high-volume instrument used for suction, viewing, and retraction that is also an ideal companion to ultrasonic scaling and sealant placement procedures. Its head and eye placement allows for exceptional 180° viewing. The design provides steady retraction of thick tongues and cheeks, allowing suction ports clear access. Made of stainless steel, the ergonomic Nu-Bird Suction Mirror is lightweight, eco-friendly, and can be fully sterilized.

SEE CLEARLY REGARDLESS OF CONDITIONS
Nu-Bird Suction Mirrors hole placement enables one to see clearly in the dark watery environment of a patient's mouth without fogging.

Suction holes are on the front and back of the mirror. The holes on the front are in direct contact with the reflective surface and are what keeps the water and debris of the mirror and out of the way for clear viewing and from fogging up. The strong suction capacity is high volume level and efficiently reduces aerosols while managing pooling water without causing tissue trauma.
The Nu-Bird Suction Mirror, formally known as "Hammer Head", design deflects oral tissue away from the suction ports making it perfect for simultaneous retraction and suction. Patients love this mirror because of its efficacy in thorough evacuation of the water keeping them from feeling like they are drowning when clinicians use the ultrasonic or other HV water spray.

We have clinically and scientifically tested this mirror for over 13 years in the following adverse conditions: thick cheeks, large thick tongues, small mouth opening, access the distal of third molars, excess blood and saliva flow, special needs patients, semi supine elderly, tall linguoverted and braces. We can confidently say the Nu-Bird Suction Mirror performs better than all other devices in its class.

Features and Benefits

Nu-Bird Suction Mirror s are changing the way professionals practice dentistry
andallow clinicians to achieve a higher standard of care.
OUR PATENTED DESIGN IS GUARANTEED TO OUTPERFORM ALL OTHERS IN ITS CLASS
Clear view while ultrasonic scaling difficult to access areas.
Efficiently removes pooling liquid on the mirror face and in the mouth.
SRP time cut in half.
Accurately place sealants in 1/3rd the time over traditional methods.
Perfect companion for water laser therapy.

Strong and steady retraction device for thick tongues, cheeks and difficult patients.
Adapter hose allows free rotation, ergonomic design eliminates body fatigue.

Scientifically proven to reduce aerosols better than traditional methods.
Long life, eco-friendly, stainless steel, fully sterilizable.
Clear fog free view with Strong and steady retraction for thick tongues, cheeks and difficult patients.
Design deflects oral tissue away from plugging suction ports maintaining suction level.
Adapter hose allows free rotation; ergonomic design eliminates body fatigue and promotes career longevity.
Replaceable #3 High Definition mirror lens.
Easily adapts to High or Low volume suction systems.
High volume evacuation performance with high velocity and extra wide air pathway for better aerosol management.
Lightweight, long life, eco-friendly, fully sterilizable, 
Made in America.
Lifetime warranty against manufacturing defects.
Can cut SRP appointment time in half.
Accurately place sealants in 1/3rd the time over traditional methods.
Perfect companion for water laser therapy.
Saves chair time and extra appointments with increased production.
Patient comfort.

SOLUTIONS DESIGNED FOR DENTAL CLINICIANS

WE STRIVE TO DESIGN,
CREATE AND PROVIDE REAL
WORKING SOLUTIONS FOR
THE DENTAL INDUSTRY.

WITH NU-BIRD'S EYE VIEW, 
WE'LL CHANGE THE WAY YOU SEE!
Share by: