Renogy E.Flex 5W Portable Monocrystalline Solar Panel with USB Port HIGH EFFICIENCY - The built-in monocrystalline solar cells give maximum efficiency and the new auto-optimization charging feature allows for a continuous charge the moment you are back in the sun. NO CHARGE DELAY  You can move this charger in and out of the sun and it will automatically determine your charging requirements and recover without any charge delay for your devices. ULTRA THIN - This charger only weighs 8.7 ounces, making it easy to transport. EASY ATTACHMENT - Includes carabiners and 4 suction cups for convenient traveling and set up. PORTABLE - Super lightweight backup charger that wont leave you stranded. Keep one in the car or backpack just in case. To enhance your user experience, we recommend you pair this product with a power bank