Russian tube 5881 / 6L6WGC / 6P3S-E "NOS".
The russian 5881 was born as 6P3S-E in the Saratov plant and was designed for the use in military vehicles and aircrafts. Outstanding mechanical sturdyness and reliability is its key feature. The original military 6P3S-E tube was made to the highest standards with tights limits in quality spread.