Each RDR K9 jacket is made from 500 Deiner Cordura, lined with officially licensed Wind Blocker 200 polortec Fleece. These “Jackets” are designed to trap core body heat, and keep your dog comfortable during long periods in inclement weather. Each jacket has multiple Velcro attachment points for I.D. patches and/or visible lights. (This Jacket does not function as a harness) Sizing is as follows: Small – Length: 12” (Measure from shoulder blade to end of rib cage) Girth: 19” – 22” (Measure around the largest point of your dog’s rib cage) Medium – Length: 17” (Measure from shoulder blade to end of rib cage) Girth: 28” – 32” (Measure around the largest point of your dog’s rib cage) Large – Length: 20” (Measure from shoulder blade to end of rib cage) Girth: 30” – 34” (Measure around the largest point of your dog’s rib cage)