This loose ring cheek can discourage fixing as it has much more movement than a fixed cheek. The hollow mouth is significantly lighter than those with a solid mouthpiece. Mouthpiece thickness: 18mm. 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.