Fan with Face Interface Bracket for 3: Built-in two high-speed silent fans, the fan speed is 7000 / min, built-in 500 mAh lithium battery, can work normally for about 3 hours. Adjustable Height: The left and right buttons can adjust the height of the mask to better fit users wearing glasses. Pulsator Adjustment: The external pulsator rotates to adjust the height of the mask bracket space Magnetic Installation: The fan has two-way magnetic suction and is easy to install and remove Fan Installation: Align the position of the mask fan base, place it at a 45 ° angle, and automatically install it with magnetic suction. Fan Emergency Power Supply: The fan consumes very little energy, provides emergency power for 3. Reduce Stress: The effective force area of the mask is increased by 95%, significantly reducing facial pressure and making it more comfortable to wear. Internal and external air circulation: With two-way air circulation, the lenses are less likely to fog up and are more