The Waterford mouthpiece is similar to a chain and can be manipulated by the horse allowing him to swallow and move his mouth freely. The bit can become uncomfortable if the horse pulls and usually stops them from leaning on it. The Waterford mouthpiece is similar to a chain and can be manipulated by the horse allowing him to swallow and move his mouth freely. The bit can become uncomfortable if the horse pulls and usually stops them from leaning on it.