The pro models from noiseblocker are extremely quiet have an auto restart function and a very long life expectancy of 140 000 hours with the help of pulse width modulation pwm the speed of the fan can be controlled via the motherboard the shape of the frame and the fan blades are the same as the normal blacksilent but are distinguished by a completely black design the mounting system for the fan is particularly sophisticated and minimizes the transmission of vibrations a large silicone