LUCKYPAW Dog Muzzle, Patented Mesh Muzzle for Large Medium Small Dogs Allows Full Pant Drinking Mouth Cover to Prevent Biting Chewing Scavenging Adjustable Breathable Mouth Guard(Black,M)Dog Muzzle Medium Sized Dogs Size M is suitable for snout circumference between 8. 75" 9. 5", and snout length longer than 2. 25" 3". The muzzle for medium sized dog is suitable for Beagle, Border Collies, etc. Note: Please Measure your dog's snout length and snout cir to get the right size muzzle according to our size chart before buying. Don't choose sizes just according to breed or past purchased sizes as every dog is unique. If between sizes,