Our take: The JG Dual electric-powered M4/M16 is a huge advance in magazine technology, lowering the cost of the highly-coveted electric powered, automatic winding M4/M16 1,000rd high capacity mag to a point where many more players are able to enjoy it without breaking the bank (just a few years ago, even a bulky electric hi-cap could easily run you over $120). A 5.8v rechargeable battery is built into the dual mag, and comes complete with charger so you never have to hassle with swapping out AA or AAA batteries. The magazine holds up to 1,000 BBs comfortably, and features a button on the side of the magazine that controls the automatic winding of the magazine. Never again will you have to rotate another hi-cap wheel with this mag, which is sure to give you a bit of a tactical advantage out on the field. Rechargeable battery is built into the mag, charger is included in the package.