USB Fan Speed Controller with Stepless Voltage Adjustment Key benefits - Precise, quiet control: stepless adjustment lets you set fan speed smoothly between low and high for the airflow and noise level you want. - Broad compatibility: works with common 5.0 V USB fans and accepts a wide input voltage range, so it adapts to USB chargers, power banks, and computer USB ports. - Extra boost for two-gear fans: supports two-gear fans that include an internal step-up board; when the fan is set to its second gear the controller provides full boost to maximize airflow. Main features and specifications - Input voltage range: DC 4 to 12 V. - Stepless output voltage: DC 2.5 to 8.0 V for smooth speed control. - Rated power: 5 W. Do not overload the controller beyond this rating. - Mechanical control: rotary knob with integrated on/off switch. Turn clockwise to increase airflow and counterclockwise to reduce airflow. - Compatibility: suitable for most 5.0 V USB fans on the market. Note that some non-adjustable fans use a 5 V direct-drive motor and will not change speed beyond their design limits. - Two-gear fan behavior: two-gear fans that include a boost step-up board can be placed in gear 2 to achieve higher airflow; when using such fans place the fan in a single gear position so the controller can regulate speed. How to use - Plug the male USB connector of the controller into a USB power source such as a phone charger, power bank, or computer USB port. - Connect your USB fan to the controller head. - Rotate the knob to switch power on and adjust speed. For two-gear fans, set the fan itself to the correct gear before using the controller for proper speed regulation. - Alternatively use a micro-USB 5.0 V power supply as the power source. Practical use scenarios - Home desk cooling: connect a USB desk fan to the controller and fine tune airflow and noise for comfortable working or studying. - Travel and camping: pair a compact USB fan with a power bank and use the controller to conserve battery by dialing back speed when full power is not needed. - Laptop and electronics ventilation: attach a small USB fan to improve circulation around a laptop or electronics and set a gentle low-speed mode for quieter operation. Important notes and warnings - Rated power is 5 W. Do not exceed this limit to avoid damage. - For two-gear fans, place the fan in a single gear position as required; otherwise the speed may not be adjustable. - Allow 1 to 3 mm tolerance for manual measurement. Color may vary slightly from photos due to monitor differences. - This controller is designed for use with USB fans and USB power sources only. Package contents - 1 x USB fan speed controller. This description reflects the product specifications and functions as provided and is intended to help you choose and use the controller correctly.