Flick the switch and this GT125 fan changes pace. Position one gives 220m3 per hour for quiet winter running. Position two lifts output to 360m3 per hour when summer heat builds. The silent German EBM motor draws 45 to 65 watts depending on speed, through a 125mm flange.
Two separate windings make the speed change clean and reliable. That helps when a grow tent sits near a bedroom and you want low extraction overnight. The fan comes with a wall-mounting bracket; the mains lead is sold separately. Duct it to a carbon filter for odour control. A one-year warranty applies.