Solid, die-cast and precision machined aluminum motor housing and base. Micrometer depth of cut control. Permanently sealed ball bearing construction. Self-releasing collet system automatically frees bit from collet when loosened. Flat top design for fast, easy bit changes. Large control knobs positioned close to base for accurate control. Fits standard plunge and D-handle bases 11A, 27,500 RPM. Includes 1/4" and 1/2" collets.