Features: Brand new and high quality USB fan air volume regulator. Strong and weak winds can be adjusted at will! Fan speed regulation principle: The non adjustable USB fan is a 5-volt direct supply fan motor, while the two speed fan has an internal boost circuit board. When placed in the second speed, the boost board raises the USB 5V and then connects to the motor, resulting in a higher air volume! The output voltage range of this stepless governor smoothly varies between 2.5V and 8.0V, and the air volume can be set arbitrarily! And the range is wider! Turning the knob clockwise can increase the air volume, while turning it counterclockwise can reduce the air volume, and the knob has a switch function! Suitable for the very common 5.0V USB fan on the market. Insert the male head of the governor into the phone charger, power bank, computer USB, fan plug, and then plug into the female head of the governor! Alternatively, use Micro USB 5.0V power supply. Specifications: Power supply range: DC 4-12V Output range: DC 2.5~8.0V Rated power: 5W Package Includes: 1 x USB Fan Stepless Governor note: No retail package. Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!