Which Lens Should I Choose?

What lenses should I choose? Do the clear lenses block UV rays? Is the mirrored lens the darkest? Can I choose to get two mirrored lenses and no clear lens?

Rex Specs What Lens To Choose Guide

These are some of the most popular questions we get about our lenses. Here are a few paragraphs that should help you make an informed decision about which lenses will be most beneficial for you and your dog.

Rex Specs size large pass the ANSI Z78.1 2010 test for impact. Testing certified by Chesapeake Testing Inc.


We offer two lenses with our goggles – one clear lens and one lens of your choice. We do this for a few reasons, but mainly because the clear lens is great for training. We actually recommend starting to train your dog to wear Rex Specs with no lenses in the goggles. This allows your dog to get used to the frames first.

Then, we recommend moving onto the clear lens, and finally to the tinted lenses. The clear lens is great because it offers the same UV and impact protection as the other lenses without changing your dogs’ perspective on the world.


We’ve learned that introducing too much at one time (the goggle frames and tinted lenses) can be a lot of change all at once for your dog. Also, as your dog is becoming comfortable with Rex Specs, there is a good chance they will paw at, or scratch the lens – so using the clear lens during this learning process keeps your second lens in perfect condition.


Ultra violet light is known to cause various types of damage to the eye.  Eye conditions in our personal dogs are why Rex Specs were born. One of our dogs had chronic sunburn to the eyelid and surrounding area due to lack of pigment, and one was diagnosed with Chronic Superficial Keratitis (pannus). This condition is a progressive change that occurs where blood vessels and scar tissue invade the cornea, and in severe cases can involve most or all of the corneal surface area resulting in blindness. Thus, having the lens be UV resistant is a must – and polycarbonate is the perfect material.

Polycarbonate has natural UV blocking properties – this allows our clear lenses to offer the same UV protection as the tinted lenses. Polycarbonate lenses are used for sunglasses, ski goggles, riot shields, and in many other applications. It’s a great material because it not only blocks 99.9% of UVA and UVB rays, but it’s also shatter resistant. Check out the video of our goggles passing the ANSI Z87.1–2010 impact resistance test (see above).

Another way to describe our lenses is by their Visible Light Transmission (VLT). This is a measurement of how much light the lens allows to pass through to the eye.

Rex Specs Lens VLT:

Clear - allows 92% of visual light to pass through 

Smoke, and Red Mirror - allows 20% of light to pass through 

Blue Mirror - allows 15% of visible light to pass through 

Silver Mirror - allows 13% of light to pass through 

So, our Silver Mirror lens is the darkest lens we offer. 

Finally, dogs do not see the same way that humans do.  They cannot focus very well on objects within 20” of their face. Also, their visual acuity is estimated to be around 20/60, whereas humans can see 20/20.  Therefore, they may not notice the scratches in the lenses as easily as we do. This is why we tell our customers to use the lenses until they're totally beat up. Check out the photo below of our dog Tuckerman with his 'used' lenses. 

If you have any other questions regarding our lenses, please send an email to or give us a call 307.203.0308 and we’ll get your question answered ASAP!

Ready for new lenses? Shop Replacement Lenses Now>>

Comment below telling us which lens you use with your dog and why!

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  • Hello, my dog was just diagnosed with pannus. What lens would you recommend for her? My residence is not considered to be high elevation.

    Donna Cormier
  • Rumour a young service dog finishing her training prefers the blue lenses. I bought two Rex Specs one of each color . Worked her in both and she leaps into the one with the blue lenses. Interesting . Anyway i got them for my other older working dogs for running with the scooter and to protect from blowing sand and such so just tried them on her for training purposes. The bonus is in the blue lenses people cant see her eyes and I had been having a trouble with certain people ( mostly older men) staring at her in not nice way and as they came up walking, leaning down intimidating her by direct eye contact . This stopped that problem completely and so she does not have people doing that behavior to her anymore and she is much happier and relaxed working in public. Did not expect this bonus.

    Nora Terrell
  • @Robert on 5/22/20,
    I work with UVC in a product I manufacture.
    UVC doesn’t reach the earth’s surface as it is filtered out by the ozone layer.

    John Burnaby

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Gear For your Dog


Lens Guide


UV Rating



Recommended Use

Red Mirror

Blocks 99% of UVA and UVB Rays.

Allows 20% of light to pass. Very similar to sunglasses.

Impact Resistant. Mirrored lenses show more scratches than clear or smoke.

Giddy up! The Red Mirror lens is great for most dogs and is very similar to the smoke lens with a bit more style.


Blocks 99% of UVA and UVB

Allows 92% of light to pass

Impact Resistant. Offers best visibility when scratched.

For Everything except protection from brightness. Great for working, hunting or adventure dogs. Blocks UV is impact resistant and often is preferred by dogs. Great training lens, and when it gets scratched the scratches are not as visible to the dog as with other lens options.

Blue Mirror

Blocks 99% of UVA and UVB

Allows 15% of light to pass. Slightly darker than smoke and red mirror.

Impact Resistant. Mirrored lenses show more scratches than clear or smoke

DM's are rolling in! The Blue Mirror lens adds a touch of flare and is one of our darker lenses for dogs who have sensitivity to light. Perfect for use in sunny areas and for those who love that blue mirror look.

Silver Mirror

Blocks 99% of UVA and UVB

Allows 13% of light to pass. Our darkest lens.

Impact Resistant. Mirrored lenses show more scratches than clear or smoke.

STYLE! Add some flavor to the daily grind with our darkest lens, allowing only 13% of visual light to pass through, making it the best option if your dog has light sensitivity.


Blocks 99% of UVA and UVB

Allows 20% of light to pass. Very similar to sunglasses.

Impact Resistant. Offers excellent visibility when scratched.

For everything! Overall the most versatile lens. Great for dogs that are rough on their equipment as it continues to offer good visibility when scratched.F

Green Mirror

Blocks 99% of UVA and UVB

Allows 15% of light to pass. Slightly darker than smoke and red mirror.

Impact Resistant. Mirrored lenses show more scratches than clear or smoke.

The Green Mirror lens adds a touch of flare and is one of our darker lenses for dogs that need some reprieve from the suns brightness.

*VLT = Visual Light Transmission

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Rex Specs

measure your dog in two steps

  1. muzzle circumference

    Measure the circumference of your dog's muzzle where you expect the goggle to land on their nose - usually around the back of their mouth.

  2. head circumference

    Measure the head circumference where you expect the goggle to land on the forehead - typically an inch or so behind the eyes.

Watch Sizing Video
Goggle Size Head Circumference Muzzle Circumference
X-Small Less than 10.5 in Less than 6 in SHOP X-Small
Small 10.5 in - 12 in 6 in - 8 in SHOP Small
Medium 12 in - 14 in 8 in - 9in SHOP Medium
Large 14 in - 17.5 in 9 in - 11.5 in SHOP Large
X-Large Greater than 17.5 in Greater than 11.5 in SHOP X-Large
Small Wide* 12 in - 15 in 6 in - 9 in SHOP Small Wide

*Designed for dogs with a wide, flat face i.e. Boston Terriers
If your dog is between sizes, select the larger size: This will insure the most functional fit and optimal field of view.

Ear Pro Fit Graphic


Measure the circumference of your dog's head at it's largest point (just in front of the ears and under the chin).



2 13" - 15" SHOP Size 2
3 15" - 17.5" SHOP Size 3
4 17.5" - 21" SHOP Size 4


Measure around the dog's neck as loose or tight as you would like the collar to fit.



1 12"-14" SHOP Size 1
2 14"-16.5" SHOP Size 2
3 16.5"-19.5" SHOP Size 3
4 19.5"-24" SHOP Size 4


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