3a thread class right-hand 0.466" thread length double hexagon head style 1.615" grip length 20 thread quantity per inch cadmium surface treated unjf thread series
Used on w/s: aircraft, eagle f-15; f-22 raptor air dominance fighter. flush (flat) countersunk (included angle - less than 135 deg w or w/o chamfer) head style
3a thread class right-hand 0.548" thread length pan head style 24 thread quantity per inch navy special project cadmium screw surface treated unf thread series