FlexSolar 8.5W Foldable Solar Charger, Waterproof Sunpower Solar Charger Panel for Power Bank, iPhone & All 5V Electronic Devices FlexSolar adapts Sunpower cell imported from USA, the efficiency can up to 21%-25%. While most monocrystalline panel is only 17%-19%. Importantly, no worries about charging under low temperature. The charging temperature is -20~70. With folded and stainless-steel eyeholes design, FlexSolar charger makes it convenient to attached on backpacks, trees, or tents, ideal for long treks. Perfect for rapidly charging all your 5V USB-charged gadgets,such as cellphones, smart phone,GPS Units FlexSolar is a wonderful helper for hiking, camping and others outdoor activities. Even in absence of power support, your device can be charged as long as there is sunlight. Integrated ETFE lamination process bring outdoor fans durable, water-resistant and lightweight solar charger. Importantly, FlexSolar is environmental friendly and energy conservative to embrace the green world with no pollution and no radiation.