When a loose ring bradoon is not comfortable for a horse because of pinching around the lips or hyper-mobility, an eggbutt is the primary alternative. By flaring out the ends of the mouthpiece and joining the rings with flush swivel joints above and below where the lips contact the edge of the bit, the eggbutt can be more comfortable for many horses, as the edges of the mouthpiece are less likely to pinch the horse’s lips.
By having rings fixed to the mouthpiece, the eggbutt does give up some mobility, in that the position of the mouthpiece is more influenced by the movement and position of the cheek pieces than by the movement of the horse’s mouth, unlike the case with a loose ring snaffle. While this in generally somewhat of a disadvantage, the fixed position could be advantageous with horses that tend to play with the bit too much.