The Dirty Dog Knuckle 53684 Sunglasses are forged with the latest lens technology in Polarised Polyfilter and Polycarbonate lenses. Polycarbonate is the most impact resistant optical material available, guaranteeing the wearer protection from physical objects as well as visual comfort. Scientifically formulated to offer exceptional defence against the sun's harmful rays, our Polarised Polyfilter and Polycarbonate lenses absorb radiation that can be damaging to the human eye. These lenses provide clear and restful vision in the most extreme environmental conditions.