Size:L neck 16-28cm, mouth 18-30cm; XL neck 20-30cm, mouth 23-34cm, XXL neck 22-35cm, mouth 28-38cm. Humane way to prevent biting unwanted chewing This muzzle is great f restraining your dog's ability to bite, chew bark while still allowing your dog to breathe, pant, drink water. Bonus collar connection strap holds muzzle in place Fit connection makes it a snap to keep your best buddys muzzle securely in place, even f the rowdy pups Easily connect it to your dogs collar use the included bonus collar f added suppt. Quality sliders f a perfect fit No cheap plastic buckles f adjusting the fit here The muzzle uses high-quality sliders f adjustments that wont loosen over time, ensuring a comftable fit f any dog. Any excess strap length can easily be secured with a hook loop fastener to prevent loose ends as well.