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. Prevents dogs from backing out of their collars Great for breeds with large necks and small heads like greyhounds Material: Nylon and Metal Additional Details ------------------------------ Product description: 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. Prevents dogs from backing out of their collars Great for breeds with large necks and small heads like greyhounds Material: Nylon and Metal