The Lenovo ThinkPad Battery 68+ is compatible with the W550, T440, T440s, L450, T450s, T450, T550, X250, and X240 systems. This 6-cell battery utilizes lithium-ion technology, allowing you to stay unplugged for longer and achieve maximum battery life. The battery can deliver approximately 72 watt-hours of power and is rechargeable. A safe power flow is ensured by over-discharge protection, which prevents damage from incorrect voltage. Each battery is secured with a chip that authenticates with Lenovo systems.