The PM202 is a battery output triode, described by Mullard as a 'super power' output valve. With an anode load of 4,500 Ohms the valve can deliver 0.3 Watts.
This is an early version with a balloon envelope and it matches the shape of the 1931 advert. Our other PM202 has the classic or shouldered envelope.
The dome carries the etched identification.
Although not easy to see the anode box is mounted horizontally.
The balloon envelope is 45 mm in diameter and, excluding the B4 base pins, is 89 mm tall.
References: Data-sheet, Data, 1040 & 1043. Type PM202 was first introduced in 1931. See also 1931 adverts.