This 27.5-gram spare battery replaces the original battery in Black Diamond Dual Fuel headlamps and LED lanternsbuy this when the original wears out or if you need an extra battery for a long trip. *Is this battery compatible with your headlamp or lantern?* Open the battery compartment and check the number: if it says 1500, this is the right battery! If not, this is not compatible with your light. - Capacity: 1500 mAh - Charging is done inside the device (headlamp or lantern) through its own charging port [Link to user manual](https://cdn.accentuate.io/7551932530851/1655860530497/BD1500-Rechargeable-Battery-Instructions.pdf?v=0) (PDF file).