Super Buckle: High quality POM buckle with 4 points lock system. Signature skull rubber: Trademark rubber skull near the D-ring, protects stitches for longer durability. Toy/Extra Small Size :  Width: 1 cm (0.4 in), Circumference: 23 - 33 cm (9 - 13 in). Recommended Breed Types: Chihuahua, Yorkshire, Greyhound, Pomeranian, German Spitz, etc. Small Size :  Width: 1.5 cm (0.6 in), Circumference: 31 - 43 cm (12.2 - 17 in). Recommended Breed Types: Poodle, Shih Tzu, Bichon Frise, Boston Terrier, Maltese, Japanese Spitz, etc. Medium Size :  Width: 2 cm (0.8 in), Circumference: 37 - 53 cm (14.5 - 20.8 in). Recommended Breed Types: Beagle, Pug, Dobermann, Shiba Inu, Corgi, Basset Hound, French Bulldog, etc. Large Size :  Width: 2.5 cm (1 in), Circumference: 45 - 70 cm (17.7 - 27.5 in). Recommended Breed Types: Golden Retriever, Dalmatian, German Shepherd, Labrador Retriever, Chow Chow, English Bulldog, Siberian Husky, etc.