This bevel bit allows mild leverage and helps with control. The sweet iron and copper mouthpiece aids salivation and acceptance of the bit. The ring is larger on the 5.5" & 6" so the bit remains in proportion with the larger horses head. Mouthpiece thickness: 16mm. Cheek height: 55mm (4.5", 5"), 70mm (5.5" & 6"). Sweet iron mouthpieces are designed to oxidize to produce a sweet taste which helps with mouthing. The addition of copper to the mouth ensures the horse will not take up too much of a contact, ideal for horses that can take a hold. Stainless steel is used for the cheeks due to it being durable, easy to clean and resistance to rust.