The curved mouthpiece on this bit allows more room in the mouth, making it suitable for horses with large tongues or small mouths. Mouthpiece thickness: 16mm. Cheek height: 50mm (4.5, 5), 65mm (5.5). Brass alloy mouthpieces are copper alloyed with a harder metal to provide warm, long-lasting mouthpieces that aid in salivation. Stainless steel is utilised for the cheeks because it is long-lasting, easy to clean, and rust-resistant.