Bombers Pelham Mullen Square TwistThe Mullen is a strong bit which creates direct pressure on the tongue which will in turn create direct pressure on the bars. Used for a strong older horse and will also bring the head down. The Square Twist will create more pressure points on the mouthpiece which will make it stronger than the Round Twist and Smooth. The mouth piece is made from blue sweet iron, because it: oxidizes easily encourages salivation helps bit acceptance is warm and sweet