This SolarGoPack product is a lightweight, portable panel and battery package that has four 5-watt monocrystalline solar panels bound together to make a 20-watt power source from the sun that charges a 12,000 mAh lithium ion battery. A single crystal or monocrystalline solid is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries. The monocrystalline structured solar panel technology is the most powerful and affordable technology on the market at this time. This 20-watt solar panel will charge a 12K mAh battery within 1 hour. The entire panel design folds up into a nice portable package for easy transport. It's great for charging any mobile devices when you are off the grid.