Happy Mouth Copper Roller Mouth 3-Ring Pessoa Gag. Pure copper is a soft, warm metal. By using 99.9% pure copper in the center of the mouthpiece, bit acceptance is improved. The taste of copper encourages horses to salivate and keep a moist mouth. Bits made of copper can have a very positive effect by promoting relaxation and softening. Excellent bit acceptance can be achieved by this combination of Apple scented space age polymer mouthpiece and pure copper center roller.