The ME41 is a magic eye tuning indicator. It has a 4.0 Volt heater and a British Octal base. The Mazda version of the octal base was not adopted by other manufacturers and is now known as the MO or Mazda Octal.
This has green lettering and our other ME41 from Mazda has white printing on the glass.
The target ratings are listed below as screen ratings.
The pinch with the voltage amplifier triode above.
The triode seen from the side.
The display: the deflector, connected to the triode anode, is the bright strip below the cathode.
The end window envelope is 28 mm in diameter, and excluding the MO base pins is 74 mm tall.
References: Data-sheet, 1040 & 1043. Type ME41 was first introduced in 1939.