Need a battery for Alienware Laptops/Notebooks with the following model numbers: 5600, 5620, 5620D; Sager 5620? BTI has you covered with our premium 8 cell LiIon battery. This product has been engineered to meet or exceed the original manufacturer's specifications and replaces the original Alienware part numbers W2CD50, 5620P-P, 87-5628S-4E3-C, 87-5628S-4D3. 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.