This AP System adapter is a necessary component designed for charging AR backpack batteries and comes as standard equipment with the AR 2000 L and AR 3000 L. In addition to its charging capabilities, the adapter may be used to power AP System products with an onboard battery slot when paired with the AP battery bag with connecting cord and necessary AP battery. This allows you to shift the weight of the battery to your hip or back, depending on whether you are using a battery belt or an AP battery backpack.