Features: brand new and high quality High-quality Material: Made of high-quality and sturdy materials and has a long service life. Wide application: Can be used on stone, glass, metal, hardwood, tile, ceramics, marble, granite and other hard materials. Used for sculpturing, dressing, precision grinding and internal grinding carbide. Eay to Use: Convenient to engrave, a good helper for improving work efficiency and polishing. The best gift for family, friends, relatives and DIY enthusiasts. Specifications: Material: Diamond Color: As the Picture Shows Product Dimension: approx. 30mm/1.18inches Net Weight: 50g/0.11lbs Package Includes: 5PCS Mini Electric Grinder Engraving Bits note: Please allow 1-2cm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Steps: 1. Hold the engraving pen with your left hand, raise the grinding for head change tool with your right hand, and turn the button lock counterclockwise to pull out the grinding for head. 2. Push down the new grinding for head, and tighten the button lock with a tool for changing the grinding for head. 3. Press in two AAA batteries (batteries are not provided), press the red power button on the side of the engraving pen, and the engraving pen will start to work. 4. The engraving pen can engrave objects such as ceramics, glass, metal and wood.