Dremel 4200-6/40 High Performance Rotary Tool with EZ Change, 47-Piece Kit Most powerful and versatile rotary tool in the Dremel line EZ Change system-change all Dremel accessories without the wrench or collet lock Cooler running with 20-percent more air flow in venting design Variable speed of 5,000 - 35,000 RPM with electronic feedback Includes 6 attachments and 40 accessories for maximum versatility