Sunnytech 3.5w 6v USB Mini Solar Panel Module DIY Polysilicon Solar Epoxy Cell Charger B034 BLOCKING DIODE INSTALLED---- A blocking diode installed already in the backside to protect the solar panel from over-charging and current backflow. SOLAR CHARGING---- Use the USB2.0 interface, it can charge power bank, MP3, MP4 and other digital products. In any sunny place, it will work for you. PORTABLE & SUFFICIENT ENERGY---- Mini solar panel, compact & stylish size, easy to be held, can be easily taken to outdoor activity. High conversion rate, high efficiency output, excellent weak light effect. HIGH QUALITY & EASY USE---- High quality epoxy resin, unique technology to make the components beautiful and strong, anti-wind and snow, increase the service life of solar panels. EDUCATION---- Solar panels are devices that absorb sunlight and convert solar radiation directly or indirectly into electricity through photoelectric or photochemical effects, it's perfect devices for science project.