Multi-Function Design: More than just a speed adjuster, this device also acts as an air volume regulator, enhancing the functionality of portable fans. Quiet Operation: Designed with a mute function, this regulator ensures a noise-free environment, perfect for work or sleep. Efficient Speed Regulation: Easily control the wind speed of your USB fan with this versatile speed controller. Suitable for 5 pieces, it allows precise adjustment to meet your cooling needs. Compact and Portable: Its mini size makes it easy to carry and use anywhere, powered conveniently by DC 5V.