Matched pair of vintage 6J4P (6Ж4П) tubes from manufacturer NEVZ, Novosibirsk (RU). Tested and measured with the L3-3 tube tester, matched in pairs. These tubes are direct replacement for the chinese 6J4 (Shuguang), EF94, 6AU6 and 6136. Do not confuse with the chinese 6J4P, that is a totally different tube. Soviet 6J4P (6Ж4П) is an upgrade for your Douk, Nobsound, etc. Please check the list of the tubes, which may be used in your amp with the manufacturer. Not less than 5000 operating hours when running under prescribed conditions. New in box tubes, directly from the factory packing. Year of production: 1969.