This D ring is made from 5/16" diameter material and has an outer diameter of 2 7/8". This D ring is slightly more compact than a normal 3 1/2" D ring. The 5/16" material adds a little more weight which helps the stability and release. Smooth, two-piece snaffle has a slight curve to the bars allowing the bit to rest comfortably across your horse's entire mouth. This mouthpiece is considered to be mild.