Used on engine, aircraft, f-108 (cfm-56, kc-135a). flush (flat) countersunk (included angle - less than 135 deg w or w/o chamfer) head style 0.281" grip length passivate surface treated
3a thread class right-hand 0.656" thread length hexagon head style 32 thread quantity per inch has offset cruciform-ribbed recess internal drive style passivate surface treated unjf thread series