2a thread class right-hand hexagon extended washer head style 18 thread quantity per inch lock serrated under bearing surface of head or washer zinc surface treated unc thread series
3a thread class right-hand 3.625" thread length double hexagon extended washer head style 9 thread quantity per inch cadmium fastener surface treated unc thread series
3a thread class right-hand 0.312" thread length hexagon head style 0.740" grip length 32 thread quantity per inch passivate surface treated unf thread series