ANSI Standard; Ground from Solid; Suited for blind hole tapping; Chamfer is 2-2-1/2 thread pitch long; Organizes 9 pieces of taps with 9 corresponding sized jobber drills. National Fine Set Includes: Tap Size: 6-40, 8-36, 10-24, 10-32, 1/4-28, 5/16-24, 3/8-24, 7/16-20, 1/2-20; Drill Sizes: 33, 29, 25, 21, 3, I, Q, 25/64, 29/64