All-day computing is a reality (up to 11 hours) when combined with a system battery on select systems. The unique ThinkPad X40 Series Extended Life Battery provides up to 3.5 hours of battery life. It connects to the bottom of the ThinkPad X40 Series notebook via the UltraBase Dock connector. Its clever design includes a retractable foot to tilt the system to a more ergonomic typing angle. The extended life battery keeps you unplugged longer and provides an integrated look and fit when you're on the move. It cannot be used with the ThinkPad X4 UltraBase Dock.