Size guide: XS: neck circumference between 22 and 28 cm Two 6 mm ropes, Biothane width 16 mm S: neck circumference between 28 and 34 cm Two 10 mm ropes, Biothane width 20 mm M: neck circumference between 34 and 42 cm Two 10 mm ropes, Biothane width 20 mm L: neck circumference between 42 and 50 cm Three 10 mm ropes, Biothane width 25 mm XL: neck circumference between 50 and 58 cm Three 10 mm ropes, Biothane width 25 mm Materials: Rope: 100% nylon Gold hardware: 100% brass Silver hardware: 100% stainless steel (D-ring and rivets), 100% chrome-plated brass (buckle and eyelets) Waterproof strap: 100% Biothane