The Shires Slotted Cheek Port Mouth Kimblewick features a port that allows more room for your horse's tongue and applies pressure to the roof of the mouth. The slotted D-rings can be used to increase leverage on the poll, making it also known as a Uttoxeter Kimblewick. This bit should be used with care. Mouthpiece thickness: 14mm. Cheek height: 100mm.