Happy Mouth Copper Roller Mouth Full CheekWe love this bit because of the space age polymer with an apple flavor combined with 99. 9% pure copper. The apple flavor allows for easier acceptance by your horse, while the copper is a better metal for keeping a moist mouth and encouraging relaxation. 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.