Increase you unplugged computing time. This high capacity battery has an extended area on the back edge and fits in the standard ThinkPad T & R Series 14W notebook battery slots. Its compatible design allows it to be in the system when the system is connected to the ThinkPad Advanced Dock, Advanced Mini-Dock, and Essential Port Replicator. Battery life (and recharge times) varies based on many factors including screen brightness, applications, features, power management, battery conditioning, and other customer preferences. (For battery life, go to lenovo.com/alldaycomputing)Lithium-Ion technology Nine-cell, rechargeable system battery, 10.8 V DC, 7.8 Ah Battery performance watt-our 84.24 Wh Standard system battery specification Over – discharge protection