Product code: Mystery 4E27 vacuum tube - 8001 transmitting top tube - 257-B tube
top Unbranded 4E27 vacuum tube
new old stock - near perfect condition but not in original box.
approximately 6" overall height
tested
The 4E27 (also know as a 257-B and 8001) was designed in the 1940's. It is a beam power tube with a maximum plate dissipation of 75 watt.