Opteka BP-SC4000 Ultra Thin Solar Powered High Capacity (4000mAh) Backup Battery and Charger for the 47st Photo Kindle 4, Kindle Touch, Kindle Touch 3G & Kindle Fire Will fully charge your mobile device using solar or USB power Ultra high capacity 4000mAh built-in lithium-polymer battery Includes 10 charging tips with USB port to maximize compatibility LED power capacity display 2 Year performance warranty