Features: These fans have a nominal voltages of 14.4V 90W and a diameter of approximately 45mm. The fans support signals stepless speed regulation, and the speed regulation board needs to be purchased separately. As long as the line is connecting in series with a 10K resistor to the positive poles, it can start. It supports a working voltages ranges of 8.5-20V and can maintain a power of 75W even under the extreme voltages of 8.5V. It is recommended to equip the power supply with a current of about 10Amp, or use electric tool power type 18650 lithium batteries or model aircraft power batteries. Specifications: Component: Plastic Size: about 45x60mm/1.77x2.36inch Working voltages: DC8.5V-20V voltages: 14.4V 90W Package Includes: 1pc Three Phase Brushless Motor note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.