Floating Prism System uses flexible silicone lens mount to absorb severe shock, impact and abuse without damage Multi-Coated Optics are state-of-art for brighter picture, higher contrast and sharply contoured images with natural color definition. Sports-Auto Focus™ System lets you focus each eyepiece to your vision once, then keeps images razor sharp from 20 yards to infinity. No more chasing focus on moving objects. N2 Injection™ system seals 14-psi pressurized dry nitrogen into the optic, for fogproof clarity in any condition - from artic cold to desert heat. Cylindrical Eyecups shield the eyes from sun, grit and wind, and can be folded down for viewing with sunglasses or gas masks. NBR Rubber Armoring is durable, slip-proof and noiseless to ensure secure, chassis protecting grip in all conditions. Makrolon® housing is durable polycarbonate with NBR Long Life rubber armoring, creating a lightweight, rugged chassis that withstands 11 Gs of impact. Impervious to harsh conditions for generations of trusted use. Ranging Reticle a versatile ranging reticle found on all "r" models that be used to judge both the height and distance to a target.