2a thread class right-hand 0.250" thread length hexagon head style 32 thread quantity per inch 3.5X0.6-6h metric thd, 7.0 mm depth, tap drill 4.5 mm into top of head unc thread series
2a thread class right-hand 0.188" thread length flat countersunk head style 56 thread quantity per inch navy special project passivate screw surface treated altered item drawing p/n MS51959-2 OR418198-2 nsn 5305007642966 unc thread series
2a thread class right-hand 0.089" thread length flat countersunk undercut head style 56 thread quantity per inch passivate screw surface treated altered item drawing from p/n's MS51959-1 unc thread series
