These teacup puppy collars are available in two tiny sizes with just the finest interfacing, making them finer and lighter for the tiniest puppies and the sensitive skin of tiny dogs. All my collars are made with light weight plastic buckles. While I love the look of metal buckles, I feel that they are too heavy for tiny puppies and dogs. XXXS Collars are adjustable from 4 1/2 to 6 1/2 inches in length and are 3/8th inches wide (10 mm). XXS Collars are adjustable from 6 to 8 inches in length and are 3/8th inches wide (10 mm). PLEASE NOTE, do not use these collars to walk your dog on a leash. Please do use a harness instead and protect your puppy's trachea. Please follow me on Instagram @ChillyPupsSabine