3a thread class right-hand 0.316" thread length flat countersunk head style 0.500" grip length 28 thread quantity per inch cadmium surface treated unjf thread series
2a thread class right-hand 0.393" thread length pan head style 32 thread quantity per inch navy special project cadmium surface treated unc thread series
3a thread class right-hand 0.544" thread length hexagon head style 0.375" grip length 28 thread quantity per inch passivate surface treated unf thread series