The lady I bought the truck from has this bulb, she lived in Halifax during WW2, this is a blackout bulb, it still works. It emits a dull reddish glow from the top circle area, enough to keep you from falling over the furniture. The harbour was a major convoy staging area and lots of German subs hung out there, it had an anti submarine net across the mouth of the harbour. Bulb used with blackout curtains.