The valve is marked CV1041 and the paper label gives PM2M. The CV1041 commercial equivalent is the PM12M. The PM12M is a variable-mu amplifier pentode with a 2 Volt filament.
The filament is for accumulator use and the anode is designed for dry battery operation with a maximum anode voltage of 150 Volts.
The classic envelope is 42 mm in diameter and excluding the B4 base pins, is 106 mm tall.
References: Datasheet & 1040. Type CV1041 was first introduced in 1933.