DRILL BITS: The hinge drill bit is made of high speed steel drill bit and designed quenching treatment shell. Superior drilling performance, high hardness and durability, reducing your working time by more than half. Suitable for woodworking professionals and enthusiasts GOOD MATERIAL: This hinge drill bit is made of brass with electroplated surface. Quality materials ensure long service life, reliability, rust resistance and wear resistance. Self-centering drill bit can make a clean and precise hole. hard and strong enough PRECISE TOOL: Adjustable design allows you to easily replace the drill. And its spring loaded outer guide with chamfer head keeps the high speed drill centered to create perfect pilot holes, they make aligning holes so much easier and you can get centered every time WIDE APPLICATION: The hinge drill bit is a standard drill bit with four sizes to meet your needs, it can provide a nice touch for wood projects or work in most quick disconnect adapters like tapping wood window or door, etc. Best choice to send a hinge drill as a gift for your father, brother or husband Specifications: 5/64": The hole diameter is about 2mm, use about 2.2-2.8mm tapping screw 7/64": The hole diameter is about 2.8mm, use about 3-3.5mm tapping screw 9/64": The hole diameter is about 3.5mm, use about 4-4.5mm tapping screw 11/64": The hole diameter is about 4.5mm, use about 5-5.5mm tapping screw