Nrc eyewear px photochromic sunglasseswith a lightweight frame that wraps around your face and adjustable pads at your nose and temples you will find the perfect fit with the px sunglasses from nrc eyewear the lens is made of a tough yet exceptionally clear polycarbonate it is then treated with a coating that gives it excellent anti scratch properties and will also prevent it from fogging up and allow water to run straight off the surface in the rain the photochromic lens adapts to changing li