2a thread class right-hand 0.880" thread length button head style 18 thread quantity per inch internal drive square socket in head cadmium or zinc surface treated unc thread series
2a thread class right-hand 1.750" thread length button head style 32 thread quantity per inch after plating rolled threads r.h. zinc surface treated unf thread series
3a thread class right-hand 1.200" thread length flat chamfer head style 20 thread quantity per inch hole in shank 1.165 in. distant from head to hole; hole 0.125 in. dia passivate surface treated unc thread series