Shires Flat Ring Eggbutt with Lozenge. Fixed rings avoid pinching, while the lozenge spreads contact over the mouth to relieve pressure on the tongue. The thickness of the mouthpiece is 14mm. Height of the cheeks: 55mm (4.5, 5.5), 75mm (5.5, 6). The most frequent material for bits is stainless steel. Durable, simple to clean, odourless, and non-rusting Stainless Steel