The 5S has a single line of etched identification. As well as the 5S the filament rating is shown. 2.3 V at 0.07 A. It is a triode on a B4 base with a split pin base.
Unlike our other 5S the inner structure can be seen under the gettering. The anode is a bright cylinder with concentric grid and single strand filament.
The right hand side of the filament is still attached to the support. The left side support is empty. The grid is a series of horizontal bars. These could be welded to the end support or they could have been stamped from a single sheet and then coiled into a cylinder.
The end of the grid cylinder.
The wide glass tube envelope is 41 mm in diameter and, excluding the B4 base pins, is 84 mm tall.