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: 21dB(A) on high setting and only 12B(A) on low speed. The 446659 VASF100T features an 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. Factory present to 15L/s for toilet installation, it may be adjusted on install to 21L/s for bathroom use and thus fully complies with current building regulations Part F&L.