Features ★ High in Efficiency: Cordless design enables more flexibility in the operation, while the speed can be freely adjust from 0 to 20000RPM. ★ Better Application: One rotary tool is more powerful than a tool box since it can be widely used on engraving, grinding, polishing, etc. ★ Has 7 Grinder Bits: There are 7pcs different grinding bit in the set, which will surely satisfy your various working needs, very practical. ★ Quick USB Charging: Equipped with a 3.6V 500mAh 18350 lithium battery, the etching pen supports USB charging, and can work for 180 minutes. ★ Simple Carrying: Compact in size and light in weight as well, the engraver pen can be conveniently carried for outdoor working. Specification: Item Type: Cordless Rotary Tool Product Model: I2C Speed: 0-20000RPM Reversible: Yes Grinding Bit Connecting Rod Diameter: Approx. 2.35mm / 0.09in Battery: 1 x built in 3.6V 500mAh 18350 lithium battery. Charging Interface: TYPE C Package List:1 x Cordless Rotary Tool 7 x Grinding Bit Package List 1 x Cordless Rotary Tool 7 x Grinding Bit