The metal engraving tool kit include 30pcs polishing bits,2 drill bits, 3 saw blades,4 stencils. Which are for beginner to work on engraving, carving, sanding, polishing, , routing, grinding, drilling, cutting. the engraving tool for metal equips with a strong motor, rotation speed can reach to 20000r/min, there are 3 position adjusting rotation speed from 5000-20000 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. The metal engraver equiped with Lithium battery and rechargable by USB interface. Cordless using will be up to 30 minutes idling after full charge.It can supply by any device with a USB interface. the metal engraving machine are convience to take anywhere you and allow you enjoy relaxing hand drill jewelry making time. The engraver pen can work on metal, glass, ceramic, leather, wood,jewelry,stone or statue. metal engraving tools are easy to operate,Create a keychain,DIY a necklace. It will not a bad to send it as gift on Christmas Day, New Year, Birthday,Father's Day. Use Newest Engraving Pen To Your Art Work Specification: Gauge:16 x 124mm Power source: USB charging Transfer Speed:5000-20000r/min. Rated voltage:3.7v Diameter of bits:2.35mm Using time:30 minutes after full charge material: metal Color as shown Package Contents: 1 X Engraving pen 1 X USB Power wire 2 X Drill bit 3 X Saw blades 30 X Bits 4 X Stencils 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.