This TMC AN/PEQ 15 Battery Box with Red Laser comes with a TMC 11.1v Lipoly Battery so all you need is just charge it up when it arrives, mount it on your airsoft gun and you're all powered up to go to a skirmish. If you intend to fit other Lipo batteries, the dimensions should be 16 x 24 x 70mm otherwise it will be tough to fit one in. This costs US$37.85 at EB Airsoft, free shipping already included.