This AN PEQ-2 Battery Pack is constructed of ABS plastic and a convenient way to store your battery on your rail system on your AEG. Recommended for 8.4V Batteries 1500-1800mah & a universal fit on all standard 20mm weaver/RIS systems. Assembled & easy to install with included mount. Great addition to your Airsoft AEG! SPECIFICATIONS UNIVERSAL FIT ON STANDARD 20mm WEAVER/RIS SYSTEMS RECOMMENDED FOR 8.4V BATTERIES (1500-1800MAH) INTERNAL DIMENSIONS: APPROX. 5IN LENGTH & 2.5IN WIDTH 1:1 REPLICA *DIRECTIONS FOR USE: THIS ITEM DOES NOT COME WITH DIRECTIONS. TO OPEN BATTERY PACK YOU MUST UNSCREW (COUNTERCLOCKWISE) THE LITTLE KNOB ON THE TOP SIDE OF THE PACK (OPPOSITE SIDE OF WHERE THE MOUNT IS) THAT HAS THE BATTERY PICTURES NEAR IT UNTIL THE PACK OPENS SO YOU CAN INSTALL YOUR BATTERY. PLEASE ALSO NOTE THAT THE KNOBS ON THE PACK THAT MAKE IT LOOK LIKE A SCOPE ETC,(THEY LOOK LIKE THEY CAN BE UNSCREWED) ARE NOT REMOVEABLE, THEY LOOK LIKE THEY CAN BE REMOVED BUT THEY CANNOT AND ATTEMPTING TO UNSCREW OR REMOVE IT WILL END UP IN BREAKING IT. THEY ARE JUST THERE FOR AESTHETIC PURPOSES AND HAVE NO FUNCTION. DISCLOSURE: Please DO NOT try to MAKE your battery fit as the connectors may detach and become damaged.