1 Exclusive Solar Technology It can automatically adjust the current and voltage to achieve maximum power delivering its fastest possible current up to 2 4A under strong direct sunlight 2 Dual USB Power 21 watt sunpower provides enough power to charge cellphone and ipad at the same time 3 Portable and frame design fits for outdoor and indoor use 4 Solar Power 21W sunpower solar panel 5 Output 1 5V 2 1A Max 6 Folded size 300x 160 x 20mm 7 Unfolded size 640 x 300 x 10mm