Sweet iron and copper encourages salivation and produces a pleasant taste in the horse's mouth. Raised copper ribs can help to prevent the horse taking too much of a hold. Three rings offer leverage options to increase severity. The 5 and smaller sizes come with shorter cheeks to ensure the bit remains in proportion with the smaller head. Mouthpiece thickness: 16mm. Cheek height: 145mm (4.5, 5), 180mm (5.5).