The Foredom K.1030 Portable Micromotor Kit features a control unit with built-in rechargeable Li-ion battery with a digital RPM display at the top that makes it easy to monitor speed as you work. The dial on the front adjusts speed from 0 to 30,000RPM. Run time is approximately 5 hours, depending on how long the micromotor is in continuous use when in battery mode, or plug it in for day-long use. Battery charge time is 3 hours. Perfect for users who work at multiple stations, or for signing/personalizing work pieces at craft and outdoor fairs when no power is available. Handpiece (motor) is small and lightweight but has plenty of power for fine detailing, polishing and even grinding on metal, wood, glass and many other materials. Its fan cooled, brush type continuous duty motor runs cool and vibration-free. It has permanently lubricated, shielded ball bearings that require no additional lubrication. The handpiece has a twist release rotary type collet for easy changes of 2.35mm (3/32) or 1/8 shank burs, depending on choice of collet installed. This kit comes with a 3/32" collet.