Ok so the other day I picked up two spiral 4" buffing wheels at lowes. One was a yellow buffing wheel and the other was white. The yellow one is very firm, yet the white one feels ridiculously soft. I've bought 6" spiral wheels before and they were pretty firm, much harder than this small white one. Is this just because they're cheap crap? And does anyone have any experience with these yellow wheels? i kinda like the firmness. Thanks for your time. Blake