Dremel 1/8" Shank Screw Mandrel is a high-speed steel mandrel with a length of 3 inches. It is compatible with Dremel Accessories 414, 422, and 429. This mandrel is used primarily with polishing bits and accessories, including the 414, 422, and 429 Dremel accessories (sold separately). Simply screw a polishing wheel or tip onto the mandrel's threaded head. For best results, insert the accessory bit all the way into the tool and then back it out slightly before tightening down. This provides plenty of shank for the collet or chuck to hold onto the bit.