Braided Round Martingale Dog Collar, Training Collar with Slidable Stop Ring and Adjustable Stopper - Ideal for Small Dogs (S(1/4") - 14" Long, Pink)EXTREME DURABLE This collar is designed to last, and won't wear or tear easily. It was sustainable to train & control hyperactive dogs. Slidable STOP RING The slidable O ring is hard to move to get it to the perfect size but that's necessary because then it won't easily move when you are using the collar in order to prevent choking. Adjustable Stopper The Stopper can be set to prevent collar slip out of dogs and increase stability. Martingale Collar