Convenient Cooling: Keep cool wherever you go with this portable USB hanging neck fan Long-lasting Power: Equipped with 2 2000mAh 3.7V (4000mAh total) 18650 batteries for extended use Durable Construction: Made from ABS and silicone materials for reliable durability Hands-Free Design: Hang it around your neck for hands-free cooling while on the move Adjustable Comfort: Adjustable fan speed and neck strap for personalized comfort and convenience Specifications: Battery Capacity: 4000mAh 3.7V (2000mAh*2) 18650 Material: ABS+Silicone Input Voltage: DC5V Charging Current: 1.8A ±0.2A Fan Operating Current: 0.4A, 0.7A, 1.1A Battery Voltage: 3.7V Fan Operating Power: 1.6W, 2.8W, 4.4W Cooling Power: 2.4W Battery Usage Time: Fan: 9.2h, 5.2h, 3.3h; Fan + Cooling Slice: 3.7h, 2.8h, 2.7h Standby Current: 20uA Motor Speed: 4000rpm, 4800rpm, 5500rpm Wind Speed: 1.29m/s, 1.43m/s, 1.72m/s Size: 185 x 219 x 56mm Weight: 370g Notes: Type-C serves as the DC5V input port. The fan cannot start during charging. Overvoltage protection is needed. During charging, the charging indicator flashes red. When fully charged, the indicator remains solid red. Button Functions: 1. Long press the fan button (1.5s) to start the fan. Short press the fan button to control the fan speed. Each short press increases the speed by one level. The fan indicator (white) increases in brightness with each level. After reaching the third level, short pressing the button stops the fan and the indicator turns off. 2. Long press the cooling button (1.5s) to start the cooling. The cooling indicator lights up. Short pressing has no effect. Long press again to turn off the cooling, and the cooling indicator turns off. When there is no external power supply, if the battery level drops below 3.2V, the fan indicator (white) flashes slowly until the fan stops working, and then the indicator turns off.