The box is 74 mm square and 135 mm long. The valve image on the box has the metal base skirt and the label stuck to one side carries the date of 5th May 1925. The box also carries basic operating details: Filament 4 Volt at 0.65 Amp and anode voltage in the range 45 - 60 Volts. The valve is retained within the box by a shaped inner sleeve with a small circular hole for the pins and a larger cut-out for the dome. The latter is part way up the sleeve to protect the pip.
 
 
 
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