Quick-release self-calibration, no need to adjust coaxiality and concentricity, and the tool head can be changed at will Insert automatic coaxial, concentric with the rotating axis, more stable and faster Comes standard with 7 commonly used grinding heads and a universal 235mm bit handle Low noise, high coaxial special bearings, effectively reduce noise and shaking Type C charging, special power battery, more convenient operation Product name:Precision grinding pen Product functions:grinding, polishing, cutting Input voltage:5V Battery parameters:10C power battery 280mA Motor speed of each gear:1st gear: 5900 rpm, 2nd gear: 8600 rpm, 3rd gear: 10500 rpm, 4th gear: 12600 rpm, 5th gear: 16200 rpm Tips:The product may be updated constantly, The Actual Product May Have Slight Differences Or Color Differences the color and appearance may be changed, please don't mind. And take a consideration before place the order if you have request for color or appearance. Colour:Gray-Black Material:Aluminum alloy Package Contents: 1 * polishing pen set Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.