K9 Optix Sunglasses for dogs are the first and only sunglasses designed just for dogs. They have a super wide nose bridge (because dogs have really big noses) and unique three strap system that keep the lenses away from the dog"s eyes and out on the bridge of the nose, where they belong. Don"t let the lenses of ordinary sunglasses touch your dog"s eyes, it could cause serious damage. With K9 Optix, you"ll be the coolest dog in town (and the safest!). These will make any canine companion look cool! So super stylish you might just want to keep them for yourself. They are the essential accessory for every fashionable canine! Features: Soft elastic adjustable head and chin straps. 100% UV protection. Anti-fog. Shatterproof. SIZE CHART: Extra Small: Dog Size: 1 - 10 lbs,Head Strap and Frame: 5 - 13 inches. Chin Strap: 3 - 7 in. Breed example: Chihuahua, Pom. Small: Dog Size: 9 - 25 lbs. Head Strap and Frame: 12 - 20 inches. Chin Strap: 4 - 8 inches. Breed example: Beagle, Westie. Medium: Dog Size: 20 - 60 lbs. Head Strap and Frame: 15 - 25 inches. Chin Strap: 5 - 11 inches. Breed example: Dalmation, Border Collie. Large: Dog Size: 50 - 100 lbs. Head Strap and Frame: 18 - 30 inches. Chin Strap: 6 - 15 inches. Breed example: German Shepherd, Labrador Retriever. Large: Dog Size: 100+ lbs. Head Strap and Frame: 22 - 45 inches. Chin Strap: 11 - 26 inches. Breed example: Large Rottweiler, St. Bernard.