Stepless airflow control for USB fans: precise, continuous adjustment of air volume from weak to strong wind to suit cooling needs and noise preferences. Simple voltage regulation knob: a small USB device that increases voltage when turned clockwise and decreases voltage when turned counterclockwise, enabling easy manual control of fan speed. Broad compatibility and easy installation: compatible with 5V USB fans available on the market; suitable for notebook cooling fans (notebook computer radiator fans) and works with phone chargers, USB power sources, and computers with USB interfaces. Compact and portable: small size with low footprint for easy storage and transport; lightweight and unobtrusive in any setup. Use scenarios: Laptop cooling: install on a 5V USB fan used with a notebook cooling pad to adjust airflow and maintain comfortable temperatures without excessive noise. USBpowered devices: connect to phone chargers or USB power banks to regulate fan speed for portable cooling or improvised cooling for small projects. DIY or compact PC cooling: employ with 5V USB fans in compact builds or peripherals, allowing onthefly speed adjustment to balance performance and noise.