This Toshiba Primary Li-Ion Battery is a lightweight, rechargeable, removable 6-cell Battery Pack designed to work with new Toshiba Libretto U100 and U105 series portable computers. It adds approximately 5 hours of battery life to your computer. If you are on the road or in meetings frequently and require non-interrupted computing time, keep one extra battery pack handy and enjoy the true portability of your PC. For a complete compatibility list please refer to the original manufacturer's web site.