Features 3 SPEED ADJUSTMENT: This electric grinding pen has 3 levels speed adjustment range of 5000-1800rpm, suitable for different materials and has a wide range of applications. HIGH CONCENTRICITY: Built in precise bearings and extended rotating shaft, effectively improving rotational concentricity, and the interchangeable copper chuck ensures stable clamping. LOW NOISE: This adjustable speed smart polishing engraving grinding tool is lightweight and portable, with low noise during operation and will not affect other work, suitable for grinding, polishing, and engraving, etc. BUILT IN BATTERY: This electric grinding pen is rechargeable, with a built in 300mAh lithium battery and a USB cable, making it convenient for you to use anytime, anywhere. SAFE TO OPERATE: This carving pen has a safe protection circuit board and smart overload chip, which will automatically cut off the power supply when the working resistance is too high. Specification: Item Type: Electric Grinder Pen Material: Aluminum Alloy Battery: 1 x 300mAh 4.2V Lithium Battery (built in battery) Speed: 5000rpm (low speed), 10000rpm (middle speed), 18000rpm (high speed) Power: 8W Package List:1 x Grinding Pen5 x Grinding Heads2 x Wool Wheels1 x Charging Cable Package List 1 x Grinding Pen 5 x Grinding Heads 2 x Wool Wheels 1 x Charging Cable