Here's a new release form SOCOM Gear designed to work best with the XCR AEG... "The Socom Gear XCR LI-PO battery is an 11.1v 1000mAh 15C battery specifically engineered and designed to fit perfectly in the XCR AEG. Its slim design was created to allow the user to fit the battery in-between the lower and upper receiver. It comes with Tamiya connectors and low resistant silver wiring. This light weight, high output 11.1v power source can deliver more power than 12v Ni-MH large type battery with only half of the size and a third of the battery cells.