Need a battery for Asus Laptops/Notebooks with the following model numbers: UL20, Pro23, X23, EEE PC 1201? 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 Asus part numbers 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.