The Pen220A from Mazda is a battery output pentode.
The anode load impedance is given as 6,000 Ohms and it would generate 1.1 Watts of audio at 7% distortion.
The literature gives 1933 as the date of introduction, however, the Mazda advert places the introduction at April 1932.
The wide spaced wire grid structure can be seen from the top of the dome as the anode cavity has an open top. The filament is a double inverted V.
The balloon envelope is 45 mm in diameter and, excluding the B5 base pins, is 96 mm tall.
References: Data-sheet, 1040, 3002 & 1043. Type Pen220A was first introduced in 1931.