2b internal thread class right-hand internal 12 internal thread quantity per inch cap drilled for attaching chain passivate surface treated cap, tube, flared unj internal thread series
2b internal thread class right-hand internal 12 internal thread quantity per inch altered from MS51532B12; u/o F100/200 acft eng cadmium surface treated cap, tube, flared un internal thread series
3b internal thread class right-hand internal 16 internal thread quantity per inch anodize surface treated cap, tube coupling, gasket seal unj internal thread series