Vacuum tube 12AU7 National (Matsushita Electric) MT9 pin 2 tubes These have been stored for a long time. They were removed from working equipment and stored as is. Heater continuity confirmed. There is some dirt on the exterior. Since they are made of glass, the dirt can be wiped off, but in the case of old vacuum tubes, the printing easily disappears, so I haven't wiped them. #VacuumTube #MTtube #12AU7 Management numbers: V018, V019