This exhibit has no identification except for the ES logo on the underside of the base cap.
A hole in the silver gettering at the centre of the dome allows a look inside. The filament is a single vertical strand and the grid wire helix is fixed to a single side support. The anode is a bright cylinder. The filament tension arm provides the top connection.
Looking under the gettering at the base the grid helix and support are better seen.
The balloon envelope is 37 mm in diameter, and excluding the B4 base pins is 78 mm tall.
