[High quality] Made of high-quality high Diamond, with nickel-plated coating, rust and corrosion resistance, high hardness, thicked diamond coating tip, good wear resistance and long service life [Precise drilling] The thickened diamond-coated tip with excellent cutting strength, enabling high-precision and smooth cutting without broken edges, perfect for drilling clean and accurate holes [Easy to use] Just start drilling at a 45 degree angle, and align the hole shape at a 90 degree angle to complete drilling, center guide holes and side holes help to easily remove chips [Size] Aperture: 8mm; Drilling depth: max 30mm; Total length: about 50mm; Bit holder diameter: about 5.5mm; Number of revolutions: Max 800/min, come with 60pcs drill bits to meet the large number of drilling needs [Applicable] It is recommended to reduce drill speeds, low drill pressure, and water is required to cool down the drill when using them, to extend drill bit life considerably. Suitable for drilling holes on