2a 2nd end thread class 12 all ends thread quantity per inch internal pressure seals to be buna n parker compound N756-75 to meet the requirements of mil-p-83461 single joint, elbow design un all ends thread series
3a all ends thread class first end bulkhead, unjf, 0.438 in. thd size, 3a class passivate surface treated single joint, elbow design unjf 1st end thread series