Happy Mouth Round Ring Eggbutt Shaped Mullen Mouth Horse Bits, 5.5 The shaped mullen mouthpiece has an inner core of twisted wire for more flexibility. The space age polymer provides for a gentler bit for a happier horse. The unique Apple scent encourages horses to accept the bit. Cheeks and rings are made of a top grade stainless steel. Mouthpieces are made of non toxic, soft, flexible and long lasting polyurethane to help protect the horse's teeth.