DOGGIE DESIGN CHOKE FREE REFLECTIVE STEP IN ULTRA HARNESS - PURPLE AMERICAN RIVER (Large) Trachea Safe - Anti-Choke Patented Design Pulls from the Chest ONLY Patented Conforming Shape Fit Seam Technology - Causes harness to conform to Dogs Chest curve. Patented Closure Slide Adjustibility - (Other copy cat harnesses have little or no size adjustment) Our 3 Inch Webbing allows for 3 Inches of Size Adjustment Safety - The Ultra is the perfect design for use as a Seat Belt Harness, PULLS from the Chest, not the Neck. Safe Night Walking Reflective strips. SIZE LARGE (Chest 19- 21). 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.