Professional grade fractional taps and dies with precision cut threads accurately formed for consistent and exact threading. Each tap and die are heat treated and tempered for file hard threads and a longer useful life. For hand threading applications only. National Coarse set includes: (6) plug taps and (6) hex dies, one each in the following sizes: 1/4-20 NC, 5/16-18 NC, 3/8-16 NC, 7/16-14 NC, 1/2-13 NC, and 1/8-27 NPT, plus an adjustable tap wrench and 1 In. die stock.