The EB34 is a double signal diode. The normal form is with external metalisation but this example clearly has never been painted. Perhaps this was a cheaper version for use where screening was either less critical or provided by a screening can.
At the top of the plastic base cap can be seen the bright copper wire that would normally be anchored to the glass as the connection for the external metal paint. This view is looking along one of the anodes. The visible rectangular plate is the central intersection screen.
The cathodes of the diodes are near the central screen with the outer metal of the anode used to dissipate heat.
A closer view.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins, is 64 mm tall.
References: Datasheet, 1040 & 1043. Type EB34 was first introduced in 1941.