Section 15 BASE METALS AND ARTICLES OF BASE METAL 83 MISCELLANEOUS ARTICLES OF BASE METAL. 83 07 FLEXIBLE TUBING OF BASE METAL, WITH OR WITHOUT FITTINGS. 83 07 90 FLEXIBLE TUBING OF OTHER BASE METAL, WITH/WITHOUT FITTINGS Commodity Code Description 83 07 90 00 FLEXIBLE TUBING OF OTHER BASE METAL, WITH/WITHOUT FITTINGS