High Quality: The double ball bearing has a service life of 65,000 hours, and the 7 blades generate strong airflow to keep the cabinet cool. Three Speeds: Silent fan features a multi-speed controller to set the fan’s speed to optimal noise and airflow levels. Low gear (L), middle gear (M) and high gear (H), the noise is only 21dB in low gear. Full Protection: Iron grill on both sides can protect your hands or prevent damage to the power cord during operation. Convenient USB Fan: The USB plug can supply power to the fan through the USB port on the back of popular audio-visual electronic equipment and game consoles. Dimension: 3.64” X 3.64” X 1.81”. Shockproof foot pads can make the fan lay flat or upright.