Reinsman Billy Allen D Ring Snaffle Bit Applies pressure to the lip on the opposite side of the face from the rein you pull. Mouthpiece, with its limited travel, is excellent for colts or a light mouthed horse. It applies a slight amount of tongue pressure for a good head set and will help pacify a nervous horse. 3" Dee. 5" Mouth. 1/2" Billy Allen snaffle.