Need a battery for Lenovo-IBM Laptops/Notebooks with the following model numbers: ThinkPad R61, R61i, T61, R400, T400, 14W 14.1 Widescreen models only (9-cells)? BTI has you covered with our premium 9 cell LiIon battery. This product has been engineered to meet or exceed the original manufacturer's specifications and replaces the original Lenovo-IBM part numbers 42T4530, 42T4531, 42T4532, 42T4644, 43R2499. 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.