Slow Twist Snaffle
This bit has a slight twist in the mouthpiece, but fewer edges than the corkscrew 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 loose ring ensures that the bit remains mobile in the horse's mouth, which can help to prevent them 'fixing' against the contact.