Martingale Dog Collars Nylon Martingale Dog Collars are a great alternative to traditional choke chains! These all-nylon collars work just like a choke collar. They tighten when a dog pulls, and relax when a dog stops pulling. Nylon Martingale Dog Collars work like a choke collar but without the chain. All-nylon collar will tighten when a dog pulls on a lead, then relaxes when the pulling stops Prevents dogs from backing out of their collars Great for breeds with large necks and small heads like greyhounds Material: Nylon and Metal Size: Collars are available in two widths and three adjustable sizes: Description Adjusts to Fit Necks 5/8" Collar 10" - 16" 5/8" Collar 14" - 20" 1" Collar 18" - 26"