KWA M4 SR10 AEG The M4 SR10 by KWA is one of the best advanced level AEGs ever produced. Built in Taiwan by totally fearsome ninja-airsoft-engineers using the most advanced internal and external parts ever made, this rifle is perfect for any airsoft enthusiast, from beginner to advanced. With a carbine length barrel, multi-position telescoping crane style stock, and high velocity output, this rifle is good for close quarters battle indoors play or any distance outdoors play. The upper receiver, lower receiver, barrel assembly, buffer tube, Rail Interface System, and magazine are all high durable aluminum alloy and the rest of the furniture is fiberglass composite. As an added bonus an ambidextrous side sling mount and detachable front and rear sights are included and already installed. The internals have been factory upgraded with a reinforced mechbox, hardened steel gears, high tension spring, high density piston, and Hi-torque/ Hi-speed motor. Because of all the reinforcement, KWA rifles are able to handle up to an 11.1v Li-Po battery, however a MOSFET is still suggested for safer operation. The rifle comes with a KWA 120 round mid capacity magazine and there are plenty of replacements available. The battery compartment is located inside the crane stock of the rifle and can be difficult to install the first couple of times. First pinch the two tabs located directly underneath the stock plate and remove the plate. Slide the cells into the appropriate tubes making sure that the wires are correctly oriented and not in any pinch points. Once everything is properly positioned, close it back up and you're ready to go. Airsoft players love this rifle for it's incredible "out-of-box" performance and great durability! Note: Does not include battery or charger