Excellent for directional control!
Good for faster work as the mouthpiece will not slide across the mouth when turning, also good for young horses as it will not pull through in a panic situation.
The 14mm normally offers extra lift from the shoulder and takes up less room in the mouth than thicker mouthpieces.
The upper cheeks can be fixed to the cheek pieces with Fulmer Loops to exert gentle poll pressure (for headlowering). We would not recommend fixing with a young horse as we would lose the play factor which is desirable for relaxed acceptance.