Vent Axia Silent VASF100HT 7.5W Extractor Fan With Humidistat White 240V - 477436 Featuring a high efficiency motor and a 100mm, 4 inch, forward curved, seven blade impeller, the Vent Axia Silent Fan delivers exceptional performance at incredibly low noise levels: Whispering away at 26dB(A) on high setting and only 12.5dB(A) on low speed, it is now officially the quietest extractor fan available. The 477436B VASF100HT features a humidistat and over run timer which permits the fan to run after you have left the bathroom. It offers two fan motor speeds for precise ventilation specific to the individual installation.