HEELE is a professional brand of pet supplies, we firmly believe that high quality and excellent service is making win-win between customer and market. That's our mission, to bring a better life and memorable time for pet owners and pets.Note: Please measure the dog need what size before order.Measurement methods: Mouth circumference: when measuring, please measure near the nose. Mouth length: dog the length from the bottom of the mouth to the neck.Muzzle Sizes Map: S - Snout Circumference: 4.7-6in/12-15 cm, Suitable For Pet Weight: 11.02- 19.8 lb M - Snout Circumference: 5.5-7.8in/14-20 cm, Suitable For Pet Weight: 22.04- 37.47 lb L- Snout Circumference: 7-9.4in/18-24 cm, Suitable For Pet Weight: 39.68- 55.11 lb XL-Snout Circumference: 8.6-11in/22-28 cm, Suitable For Pet Weight: 57.32- 158.73lbMuzzle Features: 1, Does not affect dog breathing 2, Does not affect the dog drinking Water 3, Free adjustment, very comfortableOther suggestion: Step 1: Put the muzzle where the dog can touch it, let the dog sniff It,continual praise and treat,repeat until your dog indicates that the muzzle looks interesting in a way. Step 2: Take the muzzle and gently touch it to your dog's body,slowly approaching the dog face. Give a treat. Step 3: Holding the muzzle in one hand and giving a treat in the other hand, so he needs to put his nose inside the muzzle to get the treat. Repeat until your dog seems used to the muzzle. Step 4: Put the muzzle on the dog and quickly lock the buckle treat. Removing the muzzle after several seconds. Step 5: Repeat step 4 few times until they become used to wearing the muzzle.