ON THE WAY&reg;Replacement 8.4V 6600mAh Rechargeable Battery Pack for Headlamp & Bicycle Light Replacement battery pack for Bike Light Headlamp Bicycle Head Torch. Lithium Ion 18650 rechargeable battery pack. Capacity: 6600mAh. Color: Black. Battery tested based on IEC standard to ensure capacity, quality and life time. Made of 6 x 18650 cells with PCB and poly switch for full protection This 6600mAh battery pack, easy to carry and use, would make your travel life more convenient.