The Eggbutt shape will prevent pinching of the lips. The release is slower and some slight poll pressure is introduced. The Eggbutt Gag is the gag version of the Eggbutt is stronger and will create more leverage on the mouthpiece whilst at the same time introducing more poll pressure.
The Elliptical is a 45 mm lozenge, it is stronger than the Control Plate due to it having a smaller surface area. Consequently, a horse using his tongue as a means of pushing against the bit and therefore taking control, will draw back and tuck his chin in, coming back to a better point of control.
Disclaimer: Sweet Iron will oxidize when it comes into contact with mositure, this oxidation process encourages salivation which improves acceptance of the bit. This process changes the blue colour of the Bomber bit to a brownish grey. If not used for a while, any build-up may be removed with a scourer and wiped with a damp cloth.