12V 35/50 Watt halogen.
USA 'sealed beam' style. Mandatory in the U.S. from 1939 to 1984, in either regular or halogen versions since it was forbidden to ride / drive any vehicle on a public road with replaceable light bulbs. In 1984 H-4 was finally approved and introduced. In the sealed beam the 'light bulb' is sealed into the unit and cannot be removed. These are non EU approved period correct classics!