Stay unplugged longer with the help of a spare or replacement Think Pad system battery. Increase the capacity of your original 8-cell system battery or carry an extra to extend your unplugged computing time. Its compatible design allows it to be in the system when the system is connected to Think Pad X200 Ultra Base. Features 8 Cell 14.4 V, 4.6 Ah Lithium Ion For Lenovo X200 series