It allows you to quickly charge two camera batteries at the same time. The NP-FW50 battery features 1300mAh and is rated at 7.4V for a longer run time than the Sony original. The Koah rechargeable lithium-ion battery and charger kit includes two batteries for the Sony NP-FW50 and one dual-USB charger. Equipped with premium lithium-ion cells to provide maximum battery life, the batteries also come with a 3-year manufacturer warranty. With the Koah PRO Sony NP-FW50 Two-Pack Rechargeable 1300mAh Battery and Dual Charger you can be sure you always have enough power to make it through the shoot.