Patented interchangeable lens system for dogs. The ultimate in Doggles. - Change your lens color anytime you want - for fashion or function. But more importantly our new and improved frame has been completely redesigned. Doggles ILS offers a deeper lens cup, very flexible frame, and wider nose bridge. ILS were designed from the beginning to be lighter and more comfortable for dogs. After eight years of designing eyewear for dogs, Doggles ILS has arrived. As with all Doggles, goggles for dogs, you still get the 100% UV protection, shatterproof, anti-fog lenses which Doggles are known for! xs 2-10 lbs small 9-25 lbs medium 20-50 lbs large 50-100 lbs .