Trust Sweet Iron Pony 3 Ring Eliptical BitThe TRUST Pony Collection. An anatomically shaped bit with a perfect fit for a ponys mouth. In collaboration with pony riders, TRUST equestrian developed the pony series with new sizes, thinner mouthpieces, and smaller cheekpieces. The bits are made in sizes 9. 5, 10. 5, and 11. 5. An elliptical (double jointed) mouthpiece is a standard mouthpiece. This mouthpiece has two hinges, is shaped more towards the mouth, and lies somewhat looser in the mouth.