The fixed rings prevent pinching, whilst the sweet iron mouthpiece encourages salivation, softening of the jaw and acceptance of the bit. The lozenge in the middle prevents the nutcracker action. The copper mouth ensures the horse will not take up too much of a contact - ideal for horses that can take a hold of the bit. Mouthpiece thickness: 14mm. Cheek height: 55mm (4.5", 5"), 75mm (5.5", 6"). Sweet iron mouthpieces are designed to oxidize to produce a sweet taste. Stainless steel cheeks are durable, easy to clean and resistant to rust.