The Williams cheekpiece allows for multiple rein positions. If connected to the main ring the bit acts as a loose ring, but when connected to the bottom ring it promotes pole flexion by creating more positive poll pressure. The Williams cheekpiece helps to prevent drifting.
The Buster Roller link in the middle is shortened to 40mm which increases bar and tongue pressure making the bit sharper than conventional link bits. The increased pressure on the bar will lift the head and the roller will increase pressure on the tongue bringing the chin in. Best suited for a horse with a low head carriage and which leans on the bit.