The LG3 is an EHT half wave rectifier to a specification specifically for the Wehrmacht (1936 - 1945). The L indicates a Luftwaffe design and the voltage suggests CRT EHT for an airborne display perhaps. The plug-in design certainly was for ease of servicing and replacement.
The graphs within the data-sheet show that useful current could be drawn at 5 kV, the sort of final anode voltage used for six inch cathode-ray tubes.
The shielded anode.
The wires passing through the hard glass foot are secured to the side pins that because they are secured in the Bakelite base place no strain on the glass seal - an elegant design. The insulated handle would allow for hot-swapping if required.
The three ceramic rod insulators hold the top components for the anode firmly.
The wide glass tube envelope is 26 mm in diameter and, excluding the base pins, is 70 mm tall.