The new BD 1800 Rechargeable Battery and charger is the next evolution in modular rechargeable battery pack technology. Compatible with the Sprinter 500 and ReVolt 350, the BD Rechargeable battery comes with a USB charger and is a 1800 mAh Lithium Ion rechargeable cell, giving you the freedom of reliable light you can use again and again while running, climbing and trekking in the mountains.?