Happy Mouth(R) Double Jointed Roller 2-Ring Gag Bit This Happy Mouth Bit was re-engineered with apple-scented, space-age, polymer-covered mouthpieces to help make it more gentle and more readily-accepted than traditional all-metal bits. With a circular ring that freely moves through the mouthpiece, the loose ring promotes relaxation from the horse. Typically used with two sets of reins, a gag rein and a snaffle rein, Gag Bits require gag cheeks. They work on the horses lips and poll, and are useful for horses that lean on the bit or get heavy on the forehand. They are most often used in show jumping and eventing.