Reinsman Western Dee- Billy Allen 1/2" mouth. 3" rings, 5" mouth with center roller. 
 
"The Dee ring applies pressure to the horse's cheek on the opposite side of the face from the rein you pull to allow better flexion.This mouthpiece, with its limited travel, is excellent for colts or light mouthed horses. It applies a slight amount of tongue pressure for a good headset and will help pacify a nervous horse."