Doggles ILS are the first and only protective eyewear designed just for dogs. 15 Years of experience has made our Doggles ILS (Interchangeable Lens System) the very best in pet eyewear. For eye protection or fashion, ask for it by name. Sizing: To determine proper size, measure the entire head circumference across the eyes around the entire head under the ears. To determine proper chin strap length, start measurement just under one ear, go under the chin and up to bottom of other ear.