High quality vintage soviet triodes 6N5S (6H5C) from manufacturer Svetlana, St. Petersburg ("winged C"). 6N5S is direct replacement for the american 6AS7G tubes and also for the similar soviet type 6N13S (6H13C). Black plates version. New old stock tubes in original boxes. Pairs were selected out of a bulk of tubes, which were measured with the precise RoeTest V10 tube tester. Years of production: 1967-68 (actual measurements and available pairs are in the gallery).