USB WIRELESS ENGRAVER:These engraving tool rechargable by USB interface. Cordless using will be up to 30 minutes idling after full charge. Easy to help you finish better engraved craft. VISIBLE SPEED ADJUST:Metal engraver pen equips with qualify motor. 3 position adjust rotation speed from 5000-25000 r/min to apply different situations. The lowest speed will let you polishing your nail in safe, the highest speed are also working on metal carving. VARIOUS GRINDING BITS: these metal engraving machine kit include 30pcs rotory bits,2 drill bits, 3 saw blades,1 Tungsten Steel Bit, all these bits are enough to work on engraving, carving, sanding, polishing, etching, routing, grinding, drilling, cutting. BEGIN ENGRAVED ART NOW:these portable and compact etching pen are convience to take anywhere you want and allow you enjoy relaxing hand drill jewelry making time. It can work on metal, glass, ceramic, leather, wood,jewelry,stone or statue.