Model 610 & 640 - MX Clear Lens
The lens is made of an optical Lexan material which is durable, impact resistant, and can fit the Summit, Impact, and All Sport Series Goggles. Light Transmission: 85%-95%. Good for night and Artificial Light use.
Model 610 is the Small/Medium Size lens, the 640 is the Large/XL lens.
The L/XL is larger by .08” x .79” vertically which will increase your field of view and improve your peripheral vision while wearing the goggles.