Color: black (drill core is real 4241 high speed steel) Material: aluminum alloy shell / high speed steel drill core Unique design, it is the best choice for DIY enthusiasts and professionals. The positioning accuracy does not change. Drill cuttings fall from the top of the hole and flow to both sides of the hole, which can be automatically discharged. The bit will not get stuck. It is very suitable for drilling hinges, hardware or anytime when precise positioning of holes is required. Specifications The diameter of the -5/64 inch positioning hole is about 2mm, which is very suitable for the 2.2-2.8mm self-tapping screw. The 7/64 inch positioning hole diameter is about 2.8mm, which is perfect for 3-3.5mm self-tapping screws. The 9/64 inch positioning hole diameter is about 3.5mm, which is very suitable for 4-4.5mm self-tapping screws. The diameter of the 11/64 inch positioning hole is about 4.5mm, which is very suitable for 5-5.5mm self-tapping screws. -5mm: hole diameter is 5mm, using approx. 5.5-6mm self-tapping screws -13/64 '': The hole diameter is about 5.2mm, using about 6-6.5mm -1/4 '' self-tapping screws: the hole diameter is about 6.35mm, using about 7-7.5mm self-tapping screws How to use: When opening the hole, please adjust it according to the hardness of the wood. If the wood is soft, you can choose the smaller one. If the wood is hard, you can choose the corresponding or the larger one. Compared with ordinary drill cores, the hardness is higher and sharper, and the punching efficiency is increased by 6 times. It is not limited to wooden doors and windows, but can also be used for punching operations on metal door and window hinges such as aluminum alloy, copper and stainless steel. Tips from the store: 1. The size is manually measured, please allow the error (1-3cm). 2. Due to the different monitor pixels, there may be some color difference, please refer to the actual product. 3.