ULTRA CHOKE FREE STEP IN REFLECTIVE DOG HARNESS Trachea Safe: Choke-free patented design pulls from the chest ONLY Easy to Use -Step in, wrap up and go! Designer color blended. Bonded materials for long lasting wear. 3 inch straps allow for greater adjustment. SIZE MEDIUM (Chest 16-19) IMPORTANT: Measure the CHEST only, just behind the front legs. If your dog is on the borderline between sizes, always GO DOWN to the lower size, not up. The harness needs to fit snugly to work correctly