Get a reliable, secure fit with the No! Slip Martingale Adjustable Dog Collar with Buckle. This collar's responsive limited closure buckle adjusts perfectly to your dog to eliminate slipping. The buckle's unique design also ensures you'll never have to worry about the collar becoming too tight. This dog collar is excellent for dogs that easily slip through regular collars. For dogs whose neck and head are close in size — like greyhounds — this is a common and frustrating problem. No slipping with a unique limited closure buckle Responsive buckle ensures collar is never too tight Secure, comfortable fit and feel Perfect for dogs who regularly slip through collars Available Sizes: Large: 3/4" width collar, adjustable to 18"-22" length X-Large: 1" width collar, adjustable to 22"-29" length.