Voltage: 4.2V Speed: 5000-18000r / minClamping Diameter: 2.35mm (Suitable for all 2.35MM specification grinding head, reducing drill etc)IMPROVED WIRELESS ELECTRIC GRINDER PEN: This grinding pen comes with rechargeable lithium battery, so you can use it anywhere.3 speeds: 5,000 to 18000 RPM output makes the tool more prominent. Three gear selection can apply to different situations precisely, and make your projects easier and more professional.Dual Usage: Charging and plugging in dual usage, can be connected to the power supply while charging, more efficient.Package Include:1 * Engraving pen1 * USB Power wire2 * Drill bit3 * Saw blades30 * Bits1 * Tungsten steel bit1 * Connecting stickNOTE1. It must be fully before the first use.2. Not suitable for carving, punching, cutting, grinding.3. Noise and temperature during machine operation are normal phenomena.Colour:As ShownMaterial:MetalPackage Contents:1 set x engraving machineOnly 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.