The VT-166 from Amperex is a high voltage half wave rectifier with a maximum cathode current of 250 mA.
The graphite anode is held at the sides by metal U channels that connect to the top cap. The valve identification and maker's name are on the base cap. The locating pin for the bayonet base can be seen on the right. The large metal surround at the top is probably a corona shield.
The base and pins. The Western Electric data-sheet says that a WE 148A bayonet socket fits this base.
The filament tension springs and the anode connection.
The wide glass tube envelope is 73 mm in diameter, and excluding the base pins is 217 mm tall.