Descriptions: Fits for drills, flex shafts, bench drill and hanging mill. Suitable for drilling holes on glass, shells, rocks, marble, stones, etc. Note: Add the coolant can increase work efficiency and extend service life. Specifications: Color: Silver Tone Material: Diamond, High Speed Steel Drill Bit Diameter: 2.1mm / 0.083-inch Drill Bit Length: 21mm / 0.83-inch Shank Diameter: 1.8mm / 0.071-inch Total Length: 46mm / 1.81-inch Package Content:5 x Diamond Twist Drill Bits