Used on mkn sealift support facilities program (ssep) equipment. 2a all ends thread class 12 all ends thread quantity per inch un all ends thread series
2a all ends thread class 14 2nd end thread quantity per inch special o-ring material, per mil-p-5510c, do not dupe to any other nsn un 1st end thread series
2a all ends thread class 16 1st end thread quantity per inch special o-ring material, per mil-p-5510c, do not dupe to any other nsn un 1st end thread series