In a rare successful fettling session yesterday, I replaced my brake levers, cables, etc and installed some new shimano levers (for my V brakes). I noticed they came with a small unit about the size and shape of an AA battery called a power modulator which I've also installed. It sits just above the cable guide pipe on the front brake. I've not come across these devices before and I assume its to reduce offs from sudden sharp braking, but seems a waste of time, as I'm resonably happy with my own braking abilities- unless I'm missing something. Are they worth the bother or should I remove it?