This 4-inch thick and tall curved posture collar is handmade of durable leather which will hold up to the struggling of the wearer. It forces the wearer to keep their neck perfectly straight with their chin out. It features a solid welded tri-ring on the front and a heavy locking roller buckle in back. It can be used with or without a lock. , Small Fits neck sizes 12.5 - 14.5 inches, Medium Fits neck sizes 15.5 - 19.5 inches, Large Fits neck sizes 17.5 - 21.5 inches