Battery Li-Ion 6 cell 4000mAh Part number :PA3729U-1BRS This Toshiba primary battery pack is a 6 cell , rechargeable , removable lithium ion battery . Avoid finding yourself on the road with a dead battery by adding extended power capabilities to your portable computer with an additional battery pack . Battery Li-Ion 6 cell 4000mAh Part number :PA3729U-1BRS This Toshiba primary battery pack is a 6 cell , rechargeable , removable lithium ion battery . Avoid finding yourself on the road with a dead battery by adding extended power capabilities to your portable computer with an additional battery pack . Warranty Period 1 years All product specifications depending on model and local availability. To view full listing of product and model disclaimers and legal information (e.g. spill resistant keyboard , battery life , trademarks , etc.), please click here .