The loose ring bevel allows a mild lever action with a snaffle mouth. The snaffle mouth applies pressure to the bars, squeezing the tongue. From a size 5" upwards the ring size increases to keep the bit in proportion for larger horses. Mouthpiece thickness: 12mm (4"), 14mm (4.5" - 6"). Cheek height: 55mm (4", 4.5", 5"), 70mm (5.5"). Stainless steel is the most common material for bits. Durable, easy to clean, tasteless and does not rust.