2a thread class right-hand 0.365" thread length fillister head style 20 thread quantity per inch furnished with groove between shoulder unc thread series
2a thread class right-hand 1.000" thread length flat extended washer head style 40 thread quantity per inch passivate surface treated unc thread series
3a thread class right-hand 0.539" thread length flat countersunk undercut head style 24 thread quantity per inch navy special project unjf thread series
3a thread class right-hand 0.539" thread length flat countersunk undercut head style 24 thread quantity per inch navy special project unjf thread series