King Arthur T27201 Merlin 2 Premium, 110V Variable-Speed Mini-Angle Grinder The interior includes a new motor that powers effortlessly between 0 - 13,000RPM's with improved efficiency and can be powered by an automobiles AC/DC power converter. A new high-capacity fan and extra air vents on both the neck and bottom allow the new model to stay cooler and work longer. a new motor that powers effortlessly between 0 - 13,000RPM