Guardian Gear Snake Chain Collars for dogs are an ideal dog show accessory. Lightweight collars won't create lines in the coat. Guardian Gear Medium Snake Chain Collars are 5 mm thick and available in the following lengths: 18", 20", 22", 24", 26", 28", and 30". Guardian Gear Extra-Fine Snake Chain Collars are 4 mm thick and available in the following lengths: 12", 14", 16", 18", 20", 22", and 24". Material: Chrome Sizing Guide: For choke collars, measure the circumference of pet's neck and add 2" - 3".