These Self Centering Bits are great for drilling perfectly centered holes in hinges, hardware, or any time that you need accurately placed holes. The edge tips keeps them centered even if the hole is slightly smaller than standard home door hardware. They have drill bit depth adjustments and recessed hex shafts for quick connectors. They come with HSS that are replaceable with jobber bits if ever needed. The bits are surrounded by spring loaded guides that have a widow to show the drill bit depth while making adjustments. They come in the 4 most common hinge screw sizes 5/64", 7/64",9/64", & 11/64"Description:100% brand new and high qualityThese self centering put hinges right where they should be in the center4 of the most often used sizes for carpenters, cabinet, furniture makers and other wood working tradesEasy to use and installPositioning accuracy, will not , the chips will automatic discharge from the hole on either side of the top of the drill, not stuck drill5/64'': 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 screwMaterial: High Speed SteelColor: SliverQuantity: 1 set(4pcs a set)Package includes:1 x Set of 4pcs Wood drill bit tools