Tech Rover Replacement Battery for Sony Vaio VGN-FW520F/T [No BIOS Update Required] trade; Max-Life Series 9-Cell [High-Capacity] [Black] [Plug-and-Play] Plug-and-Play, No BIOS update or system changes required. Works with all Windows Operating Systems. Tech Rover&trade; Quality product with 30-DAY Worry-Free Return Policy Brand New Battery, 6600 - 7800 mAh, Effective Capacity All Tech Rover&trade; branded items carry a 1 year warranty against manufacturer defects. 9-Cell [High-Capacity] Battery, *Please note this an extended capacity battery and may protrude slightly from your laptop.