2a thread class right-hand 0.280" thread length flat extended washer head style 32 thread quantity per inch passivate screw surface treated unc thread series
2a thread class right-hand 0.169" thread length pan head style 40 thread quantity per inch navy special project oxide screw surface treated unf thread series
3a thread class right-hand 1.375" thread length flat countersunk head style 28 thread quantity per inch passivate screw surface treated unjf thread series