3 in. Cheeks, 5 in. Mouth. 3/8 in. Smooth Copper Snaffle. Dee Ring. The Dee ring applies pressure to the horse's cheek on the opposite side of the face from the rein you pull to allow for better flexion. Copper creates moisture, packs well and keeps well in high salt areas. The 3/8 in. is a perfect all around mouth. Copper is a soft metal, watch for excessive wear.