sentences:  The MB-D10 allows the D300 to be powered by an additional EN-EL3e battery or AA batteries.An optional carrier is available which allows for an EN-EL4 or EN-EL4a battery to be installed instead.The camera can be configured to assign priority to either the internal EN-EL3e battery or the MB-D10 grip such that the other battery is used only when the primary battery is dead.