The pelham works as a direct action and leverage bit, depending on the pressure applied to the first or second rein. When reins are pulled on the first rein, equal direct pressure is exerted on the mouth. When reins are pulled on the second rein, the mouthpiece is tilted forward to apply pressure to the mouth, curb and poll.
The Low Port Mullen Barrel mouthpiece brings slight tongue relief with rein pressure, working to pressurize the sides of the tongue while pushing down on the bars. It is designed to use more bar pressure than tongue pressure, while preventing full restriction of the organ. The two sides of the mouthpiece move independently, and once the stop signal is given, it transforms into a solid piece.