???Dual ball bearings Bearings 4010 Fan - High Speed version, More 5 x Air Guide Parts :)) ??High quality Dual ball bearings, More stable and Long life, suitable for continuous work. Use time can 24 hours / day. The life expectancy is about 60,000 hours. No maintenance required. But Lubricating oil can further reduce noise. ???Rated voltage: DC 5V ???Size: 40x40x10mm ???Made by WINSINN