our exhaust fan have advantage: 1.air flow 44000m3/h, ... layer 180g/m2 Weight balance type exhaust fan (drop hammer type exhaust fan)1.mirror designed Stainless steel balde,with ... .Operating with 300 to 630 mm diameter fan blades.Available with fan guard,and without. Suitable for condensing units ... passed CE,ROHS,UL and approval.All our fan have passed CE AND IS09001 Certification tunnel ventilating fan