These are a popular jumping bit for those requiring a little extra control without putting too much severe pressure. It is especially good for horses that object to metal mouth pieces.
The Williams cheekpiece allows for multiple rein positions and can be used with equalisers or converter reins. 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 large and solid Williams cheekpiece helps to prevent drifting.
The Mullen is a strong bit which creates direct pressure on the tongue. Used for a strong older horse and will also bring the head down.
135mm = 5 1/4"