Brand New design This Rubber Mouth Dee Bit give better control of the horses head. The rubber snaffle mouth is covered with a durable rubber making it ideal for young horses or inexperienced riders.No more mistakes in buying the wrong size, less to have hanging around on your tack room wall.This innovative new bit adjusts to precisely fit any size mouth from 4 1/2 to 5 1/2. Simply twist the shanks in opposite directions and the bit size increases or decreases. No tools required. A simple concept that works.