The size of the Breakaway Cat Collars is 6.3-10.6' (adjustable range) Compatible With All Flea Collars Such as Seresto. Also fits small dogs. The Cat Collar Set contains 4 pieces of different colors (red, blue, pink,black) Cat Collar is made of Nylon. Comes with bells PATENTED REFLECTIVE STRIP TECHNOLOGY. These fabulous fluorescent collars were designed with your cats safety in mind. The width was made for optimal comfort around the neck. EASY BREAKAWAY BUCKLE. These pet collars are great for your peace of mind and cat's security.