These are known as Kokka lamps, made by the Kokka-Hana Denkyu company in Japan. Often they contain two separate filaments, which will light up individually depending on how far you screw the lamp into its socket (the end contact has a leaf-spring terminal which bends when screwed deeper into the lampholder, and makes contact to the second filament). If you Google Kokka lamp, you will find further details on these.