Samsung Galaxy S4 Battery Case, Incipio offGRID [3100 mAh] Extended Backup Battery Case for Samsung Galaxy S4 - Black Up to 3100 mAh of power for up to 15 hours of additional talk time, web surfing, downloading, or streaming Blue LED lights indicate charging and available power at a glance Charge your offGRID and Samsung Galaxy S4 with the micro USB / USB cord High density Plextonium back case and bumper is easy to install, and provides low profile protection