1/4" ~ 26tpi; 0.440"across flats; height 0.200".
5/16" ~ 22tpi; 0.525"across flats; height 0.250".
3/8" ~ 20tpi; 0.600"across flats; height 0.312".
1/2" ~ 16tpi; 0.820"across flats; height 0.375".
5/8" ~ 14tpi; 1.010"across flats; height 0.562".
3/4" ~ 12tpi; 1.200"across flats; height 0.687".