3a thread class right-hand 0.266" thread length flat countersunk undercut head style 28 thread quantity per inch phosphate screw surface treated unf thread series
2a thread class right-hand 0.270" thread length knurled no. 3 head style 56 thread quantity per inch navy special project knurled head chamfered to shank at 45 degrees unf thread series
3a thread class right-hand 0.345" thread length hexagon head style 2.562" grip length 16 thread quantity per inch navy special project end of body chamfered 0.031 in. by 45 deg phosphate surface treated unc thread series
2a thread class right-hand 1.234" thread length hexagon head style 14 thread quantity per inch washer face is undercut by shank, unthreaded portion of shank 0.998 in. min, 0.999 in. max dia uns thread series
