The new BD 1800 Rechargeable Battery is the next evolution in modular rechargeable battery pack technology. Compatible with the Sprinter 500 and ReVolt 350. Charger not included. 1800 mA-hr Lithium ion of rechargeable power. Dual-Fuel: Maximum flexibility to utilize either the rechargeable lithium ion BD 1800 Battery or Alkaline cells. Currently compatible with ReVolt 350 and Sprinter 500 headlamps. ReVolt 350 Headlamp and Sprinter 275 Headlamp sold separately.