3a thread class right-hand 0.734" thread length double hexagon extended washer head style 0.734" grip length 28 thread quantity per inch construction of extended washer is optional cadmium surface treated unf thread series
3a thread class right-hand 0.387" thread length double hexagon w/hole head style 1.615" grip length 28 thread quantity per inch navy special project cadmium surface treated unjf thread series
Used on submarine hull structure;submarine auxillary and miscellaneous systems;los angeles class ssn (688);submarine atmosphere control and compressed air/gas;ventilation. 2a thread class right-hand 0.999" thread length flat countersunk head style 13 thread quantity per inch unc thread series
3a thread class right-hand 0.553" thread length dished hexagon head style 0.552" grip length 24 thread quantity per inch cadmium surface treated unjf thread series