One of the main problems encountered with G & G ARP 9 and ARP 556 AEG is limited to the bateria.Una After installing the battery into the cylinder head space, it is difficult to replace the MOSFET, the fuse and cables inside without risk of over bending (which weakens the circuit with time). Similarly, we wanted to minimize the possibility of damaging the surface of the battery by the narrowness of the space disponible.La Battery Extension Unit (BEU) is designed specifically to provide additional space within the compartment relieving all the tensions in the components of ARP 9 & ARP 556, while protecting them to extend their durability. The BEU unit has ventilation openings on both sides to maintain a constant ventilation flow to the battery components and avoiding sobrecalentamientos.La BEU unit is designed to fit perfectly with the original design of ARP 9 & ARP 556 and requires no modifications to installation. Is made of plastic reinforced with fiber strong, flexible and impact resistant BBs nylon. · More space for the MOSFET and preventing cables kinked or damaged · Increased capacity battery Eliminates instability of the cylinder head to block the two metal rails · maximum size of the battery: approximately 152 mm long x 19.5 mm wide x 11.75 mm · once installed, the ARP ARP 9 or 556 remains as compact as before, perfect for use CQB! · also compatible with G & G CM16 Raider L2.