3a thread class right-hand 2.500" thread length headless (setscrew) head style 16 thread quantity per inch 0.062 in. dia hole drilled thru screw, 0.125 in. from socket end unc thread series
2a thread class right-hand 0.656" thread length flat chamfer head style 28 thread quantity per inch 0.188 in. dia. by 0.062 in. lg undercut directly under head unf thread series
3a thread class right-hand 1.000" thread length square head style 20 thread quantity per inch navy special project phosphate surface treated unc thread series