VEVOR Portable Ventilator, 203.2mm Heavy Duty Cylinder Fan with 10m Duct Hose, 145W Strong Shop Exhaust Blower 1020CFM, Industrial Utility Blower for Sucking Dust, Smoke, Smoke Home/Workplace

What is the diameter of the end of the exhaust hose? I have a 6-inch exhaust duct and I need to buy an adaptor/convertor to connect the hose to it

How come the smaller portable ventilator has the same level of noise as the bigger ones? Also, is the fan speed adjustable?