The energy is stored in a light-weight battery of 3.7 Whcapacity. You can operate this portable and flexible gadget in atemperature ranging from 0° to 50° Celsius. You can fold the SolarStrapto make it even more portable. When completely open, it is 290 x 97 x16 mm in size and is 144 x 97 x 25 mm in size when folded. It has an ACcharger input capacity of 5.0 – 6.0 V DC and output charge of 5.5 VDC,800 mA and it weighs around 60 g. SolarStrap Portable charger availableat Suntrica.