A Aldis day signal lamp. Day signal lamp is a signal lamp which is suitable to be used in daylight. The best known day signal lamp was also based on the latter principle and is the portable 12 volt Aldis lamp, named after the English designer Aldis. Above the lamp is a aiming visor. With a fixed resistor it is connected to the power grid or to a movable battery. The trigger switch in the handle is operated with the index finger for signalling the characters. The lamp and the plug are missing. Original case is present. Numbered A.M. 1251 Please see the photos for further details