Fast Charging Technology Auto Detect Tech delivers the fastest possible charging speed up to 2.4 amps per port or 3 amps overall under direct sunlight. The 19 watt SunPower solar panel portable charger is 21.5-23.5% efficient, providing enough power to charge two devices simultaneously. Incredibly Durable Solar Panel Portable Charger Industrial-strength PET polymer faced solar panels sewn into a rugged polyester canvas offer weather-resistant outdoor durability Dual-USB Power 19-watt portable solar panel usb charger with 3 SunPower solar panels provide enough power to charge cellphone and iPad at the same time Slim And Powerful Solar Panel USB Charger 1/3 lighter than the same power of solar silicon. The total power increased by 1/3 in comparison with the same solar panel size; eye-holes enable easy attachment to backpacks while hiking; Portable and frame design fits for outdoor and indoor use