It 's not to drill close hinge-screw pilot holes when you are installing hinges. More often than not the holes off center and the screws go in awry. do the pros install hinges so that they are perfectly aligned, and all of the screw heads are seated properly ? . They a tool called a self-centering bit. This 7pc-set of Migiwata self-centering hinge drill bits this problem. They a conic nosepiece that guides the drill to make a perfectly central pilot hole. If the nosepiece becomes clotted with wood shavings simply the bit shell by hand and the clotted shavings will come out. The set screw in the barrel body is to adjust the drill bit projection. Travel of the elastic device portion of the barrel by size and determines the top pre-drill depth. Nickel-plated steel. a replaceable HSS drill bit. These self-centering hinge drill bits it simple to drill fine holes, allowing you to put hinges far where you want them. They will your level of precision and provide you with individual satisfaction in your projects. This one of those tools that you end up wishing you had gotten years ago. : 1. : great speed steel drill bit and brass body 2. : electroplating 3. Shank : 1/4 '' hex 4. For hinge in : wood and integrative What You Will Get : 5/64 `` hinge drill bit -LRB- for # 3 and # 4 Screw -RRB- x 1pc 7/64 '' hinge drill bit -LRB- for # 5 and # 6 screws -RRB- x 1pc 9/64 '' hinge drill bit -LRB- for # 8, # 9 and # 10 screws -RRB- x 1pc 11/64 '' hinge drill bit -LRB- for # 8 screws -RRB- x 1pc 13/64 '' hinge drill bit -LRB- for # 14 screws -RRB- x 1pc 1/4 '' hinge drill bit -LRB- for # 15 screws -RRB- x 1pc 5 mm hinge drill bit -LRB- for # 16 screws -RRB- x 1pcWarranty : Within 90 days product prize is not completely contented , please CONTACT US, 100 % refund.