2b thread class right-hand 16 thread quantity per inch navy special project internal hexagonal recess 0.812 across flats by 0.300 in. deep zinc surface treated
2b thread class right-hand 20 thread quantity per inch one slot 0.135 in. min 0.145 in. max width, 0.045 in. min 0.055 in. max depth across threads cadmium surface treated