[DRILL BITS] : Hinge drill bit is made of high speed steel drill bit & quenching treatment shell designed. Superior drilling performance, high hardness and durability, reducing your working time by more than half. Suitable for professionals and woodworking enthusiasts[GOOD MATERIAL] : This hinge drill bit is made of brass and HSS with an electroplated surface. Quality material ensures long service life, reliability, rust and wear resistance. The self centering drill bit can make a clean accurate hole. fairly hard and solid[ACCURATE TOOL] : Adjustable design allows you to replace drill easily. And Its Spring loaded outer guide with chamfered head keeps the high-speed drill centered to create perfect pilot holes,They make alignment of holes so much easier and you can get center every time[WIDE APPLICATION] : Hinge drill bit is a standard bit with four size to meet you need,could make a nice touch for wood projects or work in most quick disconnect adapters like wood window or door tapping etc. Best choice to send hinge drill bit as a gift for your father, brother or husbandSpecifications:5/64": Hole diameter is about 2 mm,Use about 2.2 - 2.8 mm tapping screw7/64": Hole diameter is about 2.8 mm,Use about 3 - 3.5 mm tapping screw9/64": Hole diameter is about 3.5mm,Use about 4 - 4.5 mm tapping screw11/64": Hole diameter is about 4.5mm,Use about 5 - 5.5 mm tapping screw