This is the special 6V bulb used in the 5 inch Headlights. This bulb like our 12V bulb has a heavier filiment in it to handle shock and vibration. Sold individually.  When restoring your Headlights, don't forget to change the reflector. This helps the 6V lighting tremendously when keeping the OEM 6V system.  Our 1513B-13 fits the bill for that!