3a 2nd end thread class 12 1st end thread quantity per inch machined groove in flared end to accommodate seal ring per KC103 passivate surface treated un 1st end thread series
2a 2nd end thread class 14 1st end thread quantity per inch second end has a groove at end before threads passivate surface treated un 2nd end bulkhead thread series
Used on 92f support equipment, f-16 aircraft. 2a all ends thread class 12 all ends thread quantity per inch weapon system essential passivate surface treated un all ends thread series