Eggbutt 3-piece from Bombers.

The eggbutt prevents the horse from being pinched in the lips or corners of the mouth by the bit rings and provides a more stable feel against the horse. The eggbutt ensures that the bit stays still in the horse's mouth.
Elliptical is a three-piece mouthpiece with an elliptically shaped center piece, 45 mm long. It is sharper than the Control Plate because the contact surface against the tongue is smaller. This means that a horse that uses its tongue to push against the bit to take control will come back and tuck its nose in, making it easier to control.