A martingale collar is a no-slip, adjustable-choke collar. It is an excellent solution for dogs, such as greyhounds, who slip out of their collars. It is soft on their 'delicate' necks. A martingale collar is ideal for training as its limited closure prevents the choke from becoming too tight. This type of collar slips over your dog's head - it has no buckles, but can be adjusted by sliding the collar to make it bigger or smaller.