1. Measure under your dog's chin just behind the ears. 2.Please put your finger under the measuring tape to ensure enough space for your dog to be comfortable. 3. Attach the selected muzzle to your dog, test the fit by running your finger inside the strap. Your dog should be able to pant and move his tongue freely. About our services If you have any questions,please leave a message, we will respond to you within 24 hours and provide you with the best service. If you are satisfied with our products, please give positive feedback, we will thank you for your encouragement. Attention: The size may be slightly inaccurate due tofrom different batches of products or manual measurement;Color may be little different due to monitors.Thank you for understanding. This dog muzzle is designed for dogs with short and flat snouts, which can effectively prevent dogs from indiscriminate biting, chewing and eating.Material: PVC/nylon meshSize: XXS=19-27            XS=26-34S = 30-42            M = 38-52             L = 48 or more How to adapt your dog's muzzle: