The Bob Avila Collection by Professionals Choice Equine Short Shank Port Bit (Medium) by Professional's Choice. $76.45. AVB-110, Short Shank Medium Port Bit - This bit features a medium port that works off bar and palate pressure. The mouthpiece offers moderate tongue relief. Copper bars keep a horse's mouth moist. Good for working with older, more mature horses. This bit requires light contact. Port 2”, Mouth 5”, Cheek 6 3/4”. Save 15% Off!