I picked up some buffing wheels, Tripolli, White diamond, and this stuff at Northern tool and equipment last week. They had these polishing compounds for a few bucks each so I got the one with the blue lid. They also had one with a green lid and a few others, but no description of the contents except the obvious, no explanation of the grit, just different colored bottles. The people at the store couldn't even tell me the difference between the different bottles. What's the deal?