ACME Tandem Taps are standard hand taps which combine the initial roughing cut with a finishing cut in one step to produce an acme screw thread. Tandem design features separate roughing and finishing sections on the tap body. High speed steel straight flute acme taps produce Class 2G threads from 10 degree to 30 degree in a single pass without a lead screw. Use for tapping through-holes on steel and most non-ferrous metals. ACME Tandem Taps in sizes from 3/8" up to 1-1/2".