6S15P (6C15П) is ancestor of the more common tube 6S45P-E. It is analog to the WE437 tube, but not a direct replacement. These tubes were produced in a small scientific town of Fryazino nearby the Moskow. They have been produced until year 1969 and then replaced with the already mentioned tube 6S45P-E. High quality tubes with gold plated grid. Available tubes were in a spare parts box for the generator Г5. Tubes have been preburned. All are tested and measured with the L3-3 tube tester. Will be delivered in modern white boxes. Years of production: 1967 and 1968.