The Stentor Two was introduced by Cossor in 1927. The following year it was re-branded as the 215P and was still listed by Cossor in the mid 1930's by which time the 'New Process' filament was in use and filament consumption was 0.2 A to deliver a greater output.
Cossor also produced a 4 Volt version as the Stentor Four that was later re-branded as the 410P. The version for use with six volt accumulator's was the Stentor Six (later named 610P).
Our other Stentor Two has the paper label in better condition.
The anode and electrode supports. The silvering from the gettering prevents a clear photograph. The paper band gives practical operating conditions as well as proclaiming the design purpose - Audio Power Amplification. The 215P was also specified as a driver stage for class B output stages.
The grid can be seen to be slightly curved and lacks the flat form found in tension wound grids.
The composition base is not solid and the lead-out wires can be seen.
The balloon envelope is 46 mm in diameter, and excluding the B4 base pins is 102 mm tall.
References: Datasheet, 1043 & 1040. Type Stentor Two was first introduced in 1927.