Mesee 1/4-Inch Hex Shank HSS Countersink Tap Drill Bit Set - Back tapered beyond tap to prevent thread damage from over-drilling. - Self-centering point, no need for assistance in center drilling or center punching. - Drilling and tapping at the same time, one-step processing, improve working efficiency. Multi-use drill tap deburr countersink hex bit kit, suitable for opening, drilling hole, tapping, chamfering and deburring/countersinking on soft metal, aluminum, copper, wood, plastic. - Spiral Groove Design, within the processing thread, cutting up to exclude and was curled applied internally threaded through holes. You can also insert the screws in the hole where have been drilled. Specifications: Color: Silver Type: Tap Drill Bit Material: High-Speed Steel (HSS) Chamfer Angle: 90 Shank: 1/4" (6.35mm) Hex Shank Imperial Size: 1/8, 5/32, 3/16, 1/4, 5/16, 3/8 ➤Please Note: - The composite tap is preferably operated on a bench drill or a tapping machine. - Please add some oil before operating the tap, so the operation is smoother, and also to extend the life of the tap. - If the hand drill is used, the thickness needs to be within 2 mm, otherwise, the tap is easy to break (because the hand drill cannot always be operated vertically and at a constant speed). - Only suitable for lower hardness material which the thickness of the workpiece is less than 5mm, the soft metal thickness must be less than 3mm, Not suitable for stainless steel 304 or high hardness metal. Package Includes: 6 x Hex Shank Tap Drill Bits.