2a thread class right-hand 1.250" thread length hexagon head style 13 thread quantity per inch navy special project zinc surface treated unc thread series
flush (flat) countersunk (included angle - less than 135 deg w or w/o chamfer) head style 0.156" hole diameter 993 single pounds per square inch shear strength
3a thread class right-hand hexagon extended washer head style 28 thread quantity per inch passivate stand-offpassivate fastener surface treated unf thread series