Magicshine MJ-6092 Small and Lightweight 2 Cell Bike Light Battery, 2600mAh Li-ion Waterproof Rechargeable Bike Light Battery for MJ-900, Round Plug Magicshine Rechargeable Bike Light Battery Pack MJ-6092, 2 cell 7.2V 2600 mAh capacity. Compatible with all Magicshine bike lights with round plug, Comes default with MJ-900. Recommended only for MJ-900 and MJ-900B. For use with Magicshine 8 series bicycle lights, adapter cable MJ-6078 is needed. The battery is more ergonomic and straps neatly to your frame using one nylon strap The new waterproof battery compartment design and high quality and large area silicone non-slip mat All Magicshine batteries include BMS with over-charge, over-discharge, over temperature and short circuit protection meaning you can be sure that your Magicshine battery is safe to use and charge.