This bit has a slight twist in the mouthpiece, but fewer edges than the corkscrew or fast twist mouth. The twist in the mouthpiece causes edges that result in pressure points in the horse's mouth - it increases pressure on the tongue and bars of the mouth, and also acts on the lips. This offers the rider more control than a smooth snaffle, and can help to prevent the horse from leaning and also aids in lifting the forehand.
The single joint produces palate and bar pressure, while the full cheeks assist with steering, as pressure is applied on the opposite side of the face when the rider asks for a turn. They also help to ensure that the mouthpiece remains central and cannot be pulled through the horse's mouth.