EnerPlex Surfr Ultra Slim Battery Backup & Solar Powered Case for Samsung Galaxy S4, Black, SFG-2500-BK Battery pack can be charged by either a conventional wall charger or the integrated solar panel on the back of the case Features a 2,500 mAh battery pack Slim, yet durable design; 20mm thick Protective screen cover defends against scratches Easy to slip into pocket or purse to take with you wherever you go Ultra Slim case with integrated 2500 mAh battery which provides 100% more battery life Integrated solar panel provides emergency energy. 30 minutes of sun produces a 5 minute phone call Slimmest and lightest battery case with integrated solar that provides robust protection for your device Charge and sync via Micro-USB with smart charge feature witch charges your phone before the case LED lights indicate battery life of case and when phone is charging via solar