The 40 lumen, 4.5V to 6V LED replacement bulb is the perfect way to upgrade your old flashlights. This conversion bulb operates with any 3 cell, 4 cell, or 6V lantern or flashlight. This bulb is a 10 year bulb and allows for 100,000 hours of use before any change is required. The 40 lumens of light output provides greater value and visibility to older flashlights.