A thinner mouthpiece can make this bit a little stronger, however it may be more comfortable for horses with small mouths or large tongues. The loose rings discourage fixing. Mouthpiece thickness: 13mm. Cheek height: 50mm (4.5", 5"), 65mm (5.5", 6"). Sweet iron mouthpieces are designed to oxidize to produce a sweet taste which helps with mouthing. Stainless steel is used for the cheeks due to it being durable, easy to clean and resistance to rust.