3a thread class right-hand 0.500" thread length hexagon head style 20 thread quantity per inch navy special project top surface of the head should be marked with a of six dots unf thread series
2a thread class right-hand 0.325" thread length flat countersunk head style 40 thread quantity per inch cadmium screw surface treated unc thread series
3a thread class right-hand 0.220" thread length flat countersunk head style 40 thread quantity per inch cadmium screw surface treated unjc thread series
3a thread class right-hand 0.220" thread length flat countersunk head style 40 thread quantity per inch cadmium screw surface treated unjc thread series
2a thread class right-hand 0.138" thread length flat countersunk head style 40 thread quantity per inch silicone rubber o-ring under head zz-r-765, CL1 or CL2, grade 70 unc thread series
