The Dee ring applies pressure to the horse’s cheek on the opposite side of the face from the rein you pull for better flexion. The 3/8″ is a perfect all around mouth. Golden Glide bushings eliminate pinching for smooth movement. Mullen relief mouth for even pressure across the bars and tongue and eliminates the nut cracker effect. Copper creates moisture and packs well. It’s a soft metal, watch for excessive wear.