An ME I know uses a "dental drilling unit"(his name for it) to finish metal prototypes. He bought it used from his dentist and says it's the absolute best hand-controlled tool for fine work, and recommends it to anyone who uses Dremel-type tools for their work(me) or even hobbies, and needs more precision. It uses compressed air, not electricity, and has much more torque and rpm's than Dremel-type rotaries that have almost no torque. What is the exact name or nomenclature of this type of machine and where could I find a used one? (I have to know the correct name of it to search auction sites and dental drilling unit doesn't do it.) Thanks for any help.