The label on this valve claims it is a French Miniwatt receiving tube from the 1920's. However research shows that it matches the HF Relay both externally and in construction.
The filament connects to the end caps. The red spot at one end is matched by a red spot on the other side of the other end.
The gettering obscures most of the glass tube but a small window allows a view. The single strand filament can be seen at the left end. The filament is broken. The grid is a helix of small diameter wire mounted within the anode helix of stout wire.
A closer look at one end of the electrodes.
The thin glass tube envelope is 19 mm in diameter, and including the base pins is 73 mm tall.