Someone correct me if I'm wrong, but I've always assumed when a product lists RPMs it's talking about when using with a rotary. A PC or other DA polisher measures it's speeds in terms of OPM (Orbits Per Minute) rather than RPM. The PC7336 is variable speed ranging from 2500 OPM - 6000 OPM. I think anything that lists RPMs (for use with a rotary) you are going to want to be in the 5 - 6 (probably 6) range on a DA.