Voltage: 4.2V Speed: 5000-18000r / min Clamping 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 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 pen 1 * USB Power wire 2 * Drill bit 3 * Saw blades 30 * Bits 1 * Tungsten steel bit 1 * Connecting stick NOTE 1. It must be fully the first use. 2. Not suitable for carving, punching, cutting, grinding. 3. Noise and temperature during machine operation are normal phenomena. Colour:As Shown Material:Metal Package Contents: 1 set x engraving machine 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.