This is a Wehrmacht E.W.b power supply for use with the Torn.E.b receiver. The E.W.b "Wechselrichter" uses a vibrator unit to convert the 2V battery voltage into the 90 V required by the radio valves. The Wechselrichter comes complete with its tray to slot into the "Zubehörtornister" battery box of the Torn.E.b. (the tray is a very good copy of the original). The "Wechselrichter" is fully restored and has a new supply cable fitted to original spec. I have tested the power supply and it is in full working order.