Used on aircraft fluid system. 3b external thread class right-hand internal 12 internal thread quantity per inch anodize surface treated cap, tube, flareless
2a 1st end thread class 18 1st end thread quantity per inch supports clark model 290m; tractor, wheeled, ind., diesel driven; med dbp, nsn 24290000889384, w/rops nsn 2420010590090 nptf 2nd end thread series