Features: 1:Made of high speed steel drill and extinguish treatment shell designed, high hardness, sturdy and superior drilling performance. 2:The drill sleeve can automatically position center, apply to the installation of door hinge, which can improve the efficiency of the hinge punching. 3. Sawdust is automatically drained from the top of the holes on both sides, without drilling blocked. 4: Drilling and threading, high working efficiency. High hardness, rust-proof, stable and durable. Accuracy in positioning, do not move. 5: The bits are surrounded by spring-loaded guide lines which have a widow to indicate the drilling depth during assembly. 6:Perfect carpenter tool for woodworking, mounting hinges on wooden doors, cabinets, windows, etc. A good solid set with all most common sizes covered: Diameter of holes: 5/64" - Hole cutting diameter is about 2mm, for 2.2 - 2.8mm tap screw. 7/64"- Hole cutting diameter is about 2.8mm, for 3 - 3.5mm tap screw. 9/64" - Hole cutting diameter is about 3.5mm, for 4 - 4.5mm tap screw. 11/64"- Hole cutting diameter is about 4.5mm, for 5 - 5.5mm tap screw. 5MM - Hole cutting diameter is about 5mm, for 5.5 - 6mm tap screw. 13/64" - Hole cutting diameter is about 5.2mm, for 5.6 - 6.1mm tap screw. 1/4" - Hole cutting diameter is about 6.35mm, for 6.8 - 7.5mm tap screw. Specifications: Product Name: Hinge drill bit set Color:Silver Material: High speed steel