Helmet size chart: S: head circumference 26cm, diameter 9cm, height 5cm, adjustable strap 17-22cm; M:head circumference 32m, diameter 11cm, height 6cm, adjustable strap 20-26cm; L:head circumference 40cm, diameter 14cm, height 7cm, adjustable strap 25-37cm; Cool Look suitable for Small DogsA helmet and goggles set made especially suitable for puppies With it, you can easily dress your pet up in a different way and make it look cool. It is suitable suitable for small dogs or cats such as Teddy, Pomeranian, Bichon, Chihuahua, Yorkshire Terrier, pug, Corgi, Maltese, etc. Good ProtectionThe motorcycle helmet suitable for dogs is made of high quality ABS material, sturdy and durable to protect your dog's head. With hard lenses, doggie sunglasses are sturdy, durable, reducing UV damage to your dog's eyes. Adjustable StrapBoth the goggles and helmet contain adjustable straps that you can adjust according to the size of your pet.Cool dog helmets and glasses are suitable suitable for many occasions such as outdoors, hiking, traveling, picnics, outings, amusement parks, photography, Christmas, costume parties, etc.