We strive to provide the best bulbs for your six volt light on the market. These bulbs have two filaments so you can utilize both a bright and a dim beam, to conserve battery life. The model 10564 is a true 6V bulb for consistent, reliable operation. The BM30, our most popular bulb, can give you both a bright light and a long life, while the 4010 bulb will provide you with extra brightness but a shorter life span. All these bulbs will work effectively in a 6 volt battery system.