Made from comfy neoprene but reinforced with nylon, they are strong and durable and best of all, really comfortable for your dog to wear. Adjustable in 2 places, they are designed for all dog sizes and are available in 4 size ranges. XSmall - Neck: 8"-13" | Tummy: 9"-14" | Webbing: 3/8" Wide, Small - Neck: 10"-16" | Tummy: 13"-20" | Webbing: 5/8" Wide, Medium - Neck: 13"-22" | Tummy: 18"-29" | Webbing: 3/4" Wide, Large - Neck: 17"-27" | Tummy: 23"-39" | Webbing: 1" Wide