SPECIFICATIONS Solar Backpack with 6.5W Sunpower High Efficiencty Solar Panel Charger For Smart Phones Power Supply for Travel Hiking 17 Inch Laptop Bag Solar backpack with 6.5W solar panel , Bag material : Waterproof polyester Bag Size : 52cm*35cm*22cm bag capacity :40L Solar panel:Sunpower brand cell, High efficiencty ,transfer rate : 23.5% Power : 6.5W ,6V Accessories : 1 pcs solar bag, 1 pcs 6.5W solar panel, 1 pcs USB charging cable. FAQ: Q: How to use the product ? A: 1.Open the foldable solar charger and spread them to direct sunshine. 2.Connect foldable solar charger with mobile phone or power bank etc. through the cable, The folding solar charger will be charging devices automatically. Q:What type of solar panel you used ? A: For solar panel, we used monocrystalline solar cell ,Sunpower brand. high efficiency as 22%. Q: Is this product heavy? A:No, It is lightweight, portable and easy to take out. Suitable for mountaineering, travel, office and so on any occasion. Q: Is this product waterproof? A: The folding solar charger is weather resistant which means it will resist the occasional rain or snowed, it is not design for immersion in water. Q: Can I charge my devices in Cloudy day? A: Yes, it is ok to charging devices in cloudy day. But the charging efficiency will be lower down .and the charging time will be prolonged.