The T10 is a battery triode designed for the HF stage(s) in a radio receiver.
The vertical electrodes are supported from the pinch. The side support holds the filament tension spring.
Looking down into the dome showing the unusual control grid. A thin sheet has been punched, shaped and then bend into a cylinder. The active part of the grid is in effect five vertical tapes with the thin section facing the single strand filament.
The grid in close-up.
The triode assembly: the filament is running centrally through the anode and grid.
The joins in the anode and grid can be seen in this image.
The balloon envelope is 44 mm in diameter, and excluding the B4 base pins is 91 mm tall.