The Collar For The Adventurous Our Biothane® collars are waterproof, stink-proof, highly-durable, and feature vibrant colors to help you stand out! Our martingales use a solid brass chain, making it 100% waterproof like all our other gear! Choose from over 20 color choices. Collar Sizing Guide: Every martingale has a range of three inches. At the loosest, it should be able to slide over your pup's head and at it's tightest it should fit snugly. Martingales are not for every dog and proper use of the collar is the responsibility of the owner. Please be sure to double check your pup's collar size! Ensuring size is the responsibility of the buyer and we do not accept returns or exchanges on products where the wrong size is selected. It's always best to measure twice just to be sure!