A 5,000 round box magazine for the M4! Well, that's a lot of BBs to go around with this Laylax First Factory Dual Function Box Magazine. Made for the New Generation and Standard Tokyo Marui M4 AEGs (New Gen will need the adapter that comes with it), it's main compartment can carry 3,000 rounds and a sub-compartment that can contain 2,000 BBs. It can be winded up via a knob at the back or the regular windup at the bottom. No need for batteries.