Feature: USB Fan Air Conditioner Strong and weak wind adjustment Stepless speed regulation Fan speed regulation principle: Non-adjustable fans use a 5V direct fan motor, while two-speed fans contain a built-in boost circuit board. When set to the second gear, the boost board increases the USB 5V input to drive the motor, producing higher airflow. The stepless speed regulator provides a smooth output voltage range from 2.5V to 8.0V, allowing adjustable airflow with greater flexibility. Rotate the knob clockwise to increase airflow and counterclockwise to decrease airflow. The knob also functions as a power switch. Specifications: Power supply range: DC 4–12V Output range: DC 2.5–8.0V Rated power: 5W (Do not overload) Compatible with standard 5.0V USB fans available on the market How to use: Insert the speed controller’s male plug into a mobile phone charger, power bank, or computer USB port. Plug the fan into the controller’s output. Alternatively, use a Micro USB 5.0V power source. Attention: For two-speed fans, ensure the fan is set to the first gear before using the speed controller, otherwise speed adjustment may not work. Note: Please allow 1–3mm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the image may not reflect the actual color of the item. Package Includes: 1 x USB Fan Speed Controller