You got a red rubber never seen that before are they any good 
Red rubber is amazing, lasts ages and ages with no nicks.
Reason I made the split is for an easier bending and fine tuning, plus I also slightly pull the dog ear outwards as well so it's nearer the tip of the rubber edge.
It won't bend out if shape unless you really pushed hard, I mean very hard.
Kempy, yeah just a little 3/4 cm split and some pliers, simple and so effective, I'd known about it for years and never done it, thinking its just a fad, but when I tried it, I couldn't believe the difference!