Need a battery for Toshiba Laptops/Notebooks with the following model numbers: Satellite P500, P505, P505D; Qosmio X500, X505? BTI has you covered with our premium 6 cell LiIon battery. This product has been engineered to meet or exceed the original manufacturer's specifications and replaces the original Toshiba part numbers PA3729U-1BRS. All BTI batteries are manufactured and tested under our stringent quality standards and come with an industry leading 18 month manufacturer's warranty. BTI... True to the original.