2a thread class right-hand 0.500" thread length flat chamfer head style 56 thread quantity per inch chromate zinc screw surface treated unc thread series
3a thread class right-hand 0.351" thread length flat countersunk head style 24 thread quantity per inch cadmium screw surface treated unjf thread series
3a thread class right-hand 1.417" thread length flat countersunk head style 28 thread quantity per inch cadmium screw surface treated unf thread series