Cowhide Leather. Nickel-Free Metal Hardware. Posture Collar dictates obedience to posture. Locking buckle closure. Solid metal D-ring faces forward for easy attachment. Fits collars 14 inches to 18 inches. Ingredients: 50% Cowhide Leather, 35% Polyester, 15% Nickel-Free Metal. Includes: 1 Soft Lined Leather Posture Collar *Fits collars, inner diameter 4.63 inches to 6.27 inches.