Stainless steel. 14 mm mullen mouthpiece with fixed cheeks, linked to each other with a stainless steel bar. Keeps the cheeks from becoming entangled with the reins or the cheeks of other bits when driving several horses. 3 rein slots.Sizes 115 and 125 = branches with 2 holes.Sizes 135 to 165 = longer branches with 3 holes.