This 1.23" x 0.25" indicator lamp will replace both  3V and  6V,  250mA, fuse type lamps.  It was used by many of the vintage stereo receiver companies to back light tuner and control panel displays. This fuse lamp was very popular back in the 70's and 80's. Some of the manufacturers that used fuse lamps in their receivers and component systems include: Marantz, Sansui, Fisher, JVC, Protron, Lafayette, Panasonic, McIntosh, Pioneer and many others. The fuse will be somewhat dimmer when replacing a 3V fuse lamp and a little brighter if your replacing a 6.3V fuse light.