This bit allows the rein to be placed on either the main ring or smaller lower ring for more leverage whilst the copper lozenge encourages the horse to salivate. The 5" and smaller sizes of this bit have smaller rings to ensure the bit remains in proportion. Mouthpiece thickness: 16mm. Cheek height: 120mm (4.5", 5"), 145mm (5.5", 6"). Stainless steel is the most common material for bits. Durable, easy to clean, tasteless and does not rust. Copper is used in the mouthpiece, creating warmth and encouraging salivation to keep the mouth soft.