3a 1st end thread class 12 1st end thread quantity per inch machined groove in flared ends to accommodate seal rings per KC103 passivate surface treated un 1st end thread series
Used on aircraft, stratolifter c-135, eagle f-15, and f-16; support equipment for the f-4, t-37, & t-38 aircraft. 3a all ends thread class 20 1st end thread quantity per inch weapon system essential unjf 2nd end thread series
3a external thread class right-hand external 0.641" overall length passivate surface treated plug, tube fitting flared (note: drilled hole is optional should not be considered as a separating characteristic unf external thread series