The I.K. 91 is a very light weight and very comfortable glasses. The multilayer foam fits on your face like a soft pillow so it is very easy to use for long periods of time.
The spherical lens gives you a wide field of vision with totally clear peripheral vision.
The color of the mirror lens is a blue / black or red gradient to provide sun protection from above while still allowing you to see the ground clearly below the narrow headband easily fit over or under your helmet.
All IK91 lenses provide 100% UV blocking and are impact resistant.