A Ring cheekpiece introduces poll pressure as well creating leverage on the mouthpiece, the 2½ Ring version is the softest version of ring bit as the ½ ring softens the leverage on the mouthpiece and poll.
The Elliptical Lock Up is a double break bit with a "locked" lozenge in the center. 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.
By Locking up the Elliptical joint, it removes any nutcracker action, meaning it will bear less pressure on the horse's bars. It in turn applies more tongue pressure than the Ported Kernel style bit, making it a stronger choice.