Tenergy 1-4 Cells Li-PO/Li-Fe Balance Charger with 7.4V 1200mAh 20C Short Stick LiPO Battery Pack for Airsoft guns Built-in balancer. Batteries are automatically balanced during charging, ensuring full charge Advanced individual charging method-charge each cell individually Fits 1S to 4S Li-PO/Li-Fe battery packs with XH type balance connector Charge Rate: 1A (1,000mah per hour) This 7.4v Li-Po battery can deliver more power than 7.2v Ni-MH large type battery with only half of the size and a third of the battery cells.