The moisture meter can quickly measure the moisture content of the grain. 1. The fan starts working when connected to the solar panel and can also draw power from other USB devices such as power bank, computer, etc. 2. Portable, small size, easy to carry. No batteries required, super quiet and green energy, environmental protection. 3. There is no battery in the fan. If you need a fan to work at night, you can use a power supply. 4. When connected to the solar panel, the way the fan works depends on sunlight. When the sunlight is strong, the fan works quickly. 5. Great combination, suitable for greenhouse, dog kennel, trailers, motorhomes and so on. Specification: Item Type: Solar Panel Material: Iron Color: as shown in the picture Solar panel size: approx. 14,5 x 14,5 cm / 5,7 x 5,7 inch Cooling fan size: approx. 13,5 x 15 cm / 5,3 x 5,9 inch Weight: about 353 g/12,5 oz Solar Panel Power: 5W, 6V Power supply: USB 5v plug Application: suitable for greenhouse, dog kennel, trailer, motorhome and so on List of packages: 1 x Solar Panel 1 x Fan Note: 1. Without electricity storage function.