Need a battery for HP Laptops/ Notebooks with the following model numbers: 6520s? BTI has you covered with our premium 6 cell Li Ion battery. This product has been engineered to meet or exceed the original manufacturers specifications & replaces the original HP part numbers 451545-251, 451545-361, 456623-001, HSTNN-OB51, STL-CHA-SON, NBPGA73. All BTI batteries are manufactured & tested under our stringent quality standards & come with an industry leading 18 month manufacturers warranty. BTI... True to the original. Features Power Type: Li Ion Power: 11.1V, 4400m Ah Product Warranty: 18 Month ADV Compatibility: HP Compaq 6520s OEM P/N: 451545-251, 451545-361, 456623-001, HSTNN-OB51, STL-CHA-SON, NBPGA73