The concept of the original Dremel Moto-Tool was to rotate a bit at high speed, the bit being held in a collet. Variable-speed versions may cover a range of 3,000–37,000 RPM. The Dremel concept relies on high speed as opposed to the high torque of a conventional power drill. By inserting an appropriate bit (or burr) the tool can perform drilling, grinding, sharpening, cutting, cleaning, polishing, sanding, routing, carving, and engraving. Both battery-powered and corded models are available. Early cordless models were marketed as the Dremel Freewheeler. Dremel options include a miniature planer attachment and a saber saw attachment that lets the tool act much like a small reciprocating saw.