Many of us dont own a pair of prescription sunglasses so these adjustable sunglasses are a summer essential their ingenious double lenses can be constantly adjusted for short or long sight simply by turning the tiny dials on the side with a lens power range from 600 d for short sightedness to 300 d for reading and they also offer full uva and uvb protection nb adjustable focus eyewear is not intended to replace prescription eyewear or examinations by eye care professionals never disr