The TS4 is a general purpose triode that was introduced in 1926. The envelope has a milky appearance suggesting that this was originally gettered but now has lost its vacuum.
The filament was originally a single vertical strand but now is missing. The grid is formed from five strips held between small end cylinders. The strips are twisted as they pass into the cylindrical anode so as to be end on to the length of the filament.
The remains of the filament are visible in the fold of the tension spring.
The grid strips close into the anode space and pass within about a mm of the filament.
In close-up the grid strip orientation can be seen.
The highly corroded base pins are of simple split pin construction.
The balloon envelope is 44 mm in diameter, and excluding the B4 base pins is 88 mm tall.
Reference: 1043. Type TS4 was first introduced in 1926.