The MB 01 stainless mouth has copper inlay for improved bit acceptance. The hooks are slots on the ring of the bit that allow you to secure the position of the bridle and the reins on the cheek ring of the bit. The top hook can be attached to the cheek pieces of the bridle and stabilizes the bit inside the horse's mouth. The rein hook allows the rider more leverage. Condition: Used - Very Good - Light scratches on mouthpiece Size: 5"