Package Dimensions: 13.2 x 12.9 x 1.7 cm; 310 grams Finish: Silver Material: High Speed Steel Batteries Included: No Battery(s) / Battery Required: No Spare Parts Availability: Spare Parts Information Not Available If You Discovered Them Before, Now Your Holes Are Now Perfectly Centered! Features: 1: Made of high speed steel drill bit and quenching treatment shell designed, high hardness, sturdy and superior drilling performance. 2: The drill guide can automatically position the center, applicable to the installation of door hinge, which can improve the drilling efficiency. of hinge punching. 3: Sawdust will be automatically discharged from the top of the holes on both sides, without stuck drill bit. ?A Good Solid Set with All Most Common Sizes Covered?? 5/64" - about 87mm in total length, hole diameter is about 2mm is designed for 2.2-2.8mm tapping screw; 7/64" - about 90mm in total length, hole diameter is about 2.8mm is designed for 3-3.5mm tapping screw; 9/64"-With 94mm total length, the hole diameter is about 3.5mm for 4-4.5mm tapping screw; 11/64"-about 100mm total length, the hole diameter is about 4.5mm for 5-5.5mm tapping screw; 5MM - about 108mm total length, the hole diameter is about 5mm is designed for 5.5-6mm tapping screw; 13/64" - 109mm total length, the hole diameter is about 5.1mm for 5.6-6.1mm sheet metal screw; 1/4" - About 113mm total length, the hole diameter is about 6.3mm is designed for 6.8-7.2mm sheet metal screw. Specifications: Product Name: Self Centering Hinge Drill Bits Color: Silver Material: HSS Package Includes: 8 * Self Centering Drill Bits 1 * Hex Keys