Up for sale is a vintage Amperite 22-4 current regulator (ballast) tube in its original red and black box. This is a New Old Stock (NOS) unit, manufactured in Union City, N.J..
These ballast tubes are essential for protecting vintage radio and audio equipment by automatically controlling current and voltage fluctuations. As the box states, they are designed to "prolong the life of tubes, sets, and other apparatus".
Condition: NOS (New Old Stock) in original box.
The glass envelope is clear, and the internal zigzag filament is perfectly intact.
Base: Standard 4-pin base in excellent condition.