Union Butterfield 1585OV(UNC) High-Speed Steel Spiral Point Tap, Uncoated (Bright) Finish, Round Shank With Square End, Plug Chamfer, 3/8"-16 Thread Size Spiral point tap pushes chips ahead of tool to reduce clogging Spiral point tap with straight flutes for cutting threads in through holes Oversized by .005 to allow for material added by plating or heat-treating after tapping Relieved-style design reduces friction between tap and workpiece for reduced tool wear Plug chamfer for easier starting and correct perpendicular alignment