The Professional's Choice Bob Avila Medium Port Bit works off bar and palate pressure. The mouthpiece offers moderate tongue relief. Good for working with older, more mature horses. This bit requires light contact. NOTE: This bit will rust when exposed to moisture. This creates a sweet taste in the horse's mouth and promotes salivation.Professionals Choice has revolutionized the equine industry through diligent scientific research and producing the highest quality products strictly for the horse's safety and well-being. Pro Choice tack, sport boots, saddle pads, and much more are sought after by trainers and riders the world over.