⭕ 4212H GEC STC Western Electric V1505 4212D 212 pip top triodes pair tubes valve
This sale is for an impressive pair of PIP TOP transmitting audio triode type 4212H or simply 212H GEC.

Though the STC logo was initially made for Western Electric in America under the name 212 and then distributed to various UK valve manufacturers those days including ITT STC and GEC.
The 4212H or 212H shares similarity with the 4212D (212D) made by Western Electric and the Mullard MZ2-200 .
Tubes like this one were used for audio amplification, according to the spec sheet, the plate could dissipate 275 watts. Filament voltages is 14 volts at 6.2 amps, the plate voltage was 3,000 volts, maximum.
It is about 300m tall!