Features: Insert governor into phone charging treasure, insert the fan USB plug into the USB port of governor, and then turn the adjustment knob to adjust. Stepless speed regulation output voltages ranges 5V-30V stable change, so speed of the fan can be adjusted, greatly the comfort. Crafted from ABS, features USB input and a simple twist operation—clockwise to increase and counterclockwise to decrease fan speed for comfort. Suitable for hot day at your desk, in your dorm room, or while traveling, this USB fan controller transforms any ordinary fan into a customizable cooling experience. There is no voltages boosting function, which is mainly used to adjust the speed of the motor, USB male input and USB female output. and it cannot speed electronic products with built-in batteries. Specifications: Component:ABS Size:Approx.77x50mm/3.03x1.97inch Package Includes: 1Pc Speed Controller note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual of the item.