Most run at a set rpm, 1300-1500, something like that range. The better ones run higher 3000rpm on Baldor. Others are adjustable (variable speed). Mine is like this. It's capable of programming. I can program in a range of speed. Thus, I can quickly change the rpm I'm working at, depending on what I desire to do. i.e. lop off more metal, sand slower, not eat up much soft metal, ect.. Sometimes I work it with a knobby tire or smooth wheel. Yes, I do have kevlar gloves and sometimes I wear them. DM