The Eggbutt cheek piece prevents pinching of the lips and gives a solid feel against the side of the face. It also prevents the bit being pulled through the mouth. The release is slower than the loose ring and also introduces light poll pressure.
A ring cheek piece introduces poll pressure as well as creating leverage on the mouthpiece, the 2½ Ring version is the softest out of the 3 or 4 ring alternatives as the ½ ring softens the leverage on the mouthpiece and poll.The Elliptical is stronger than the Control Plate due to it concentrating pressure onto a smaller surface area. This bit will suit a horse that pushes the bit with its tongue. The horse will draw its head back and tuck its chin in, finding a better balance of control.