This battery is the industry standard; the 8.4v 1600mAh NiMh mini-type battery. This is used in full-stock guns (e.g. AK47, Steyr AUG etc), front wired M4 Carbines, FAMAS and many more! Manufactured by Intellect for Swiss Arms, this is one quality product that will last a long time in the field, as well as many charge/discharge cycles. The 8.4v is perfect for out of the box guns, and provides more than enough current whilst not being too stressful on the internals.