3b thread class right-hand 16 thread quantity per inch navy special project three equally spaced lugs on nut 0.240 in. mon hght with drilled holes 0.100 in nom dia
0.409" hole diameter 0.499" outside diameter 0.020" material thickness w/5 external straight keys, 0.120 in. wide by 0.078 in. long, 90 degree angle between first key key