Or, they can be attached to a branched duct system with picks ups in two or three locations. This makes them a good choice for large houses. If properly rated, the fan could be attached to a range hood. Some units can accept a duct from the range hood. Most operate at two or more speeds.
Several manufacturers sell complete kits with all the ducts and accessories.
These may cost a bit more, but the kits simplify installation. If you want balanced operation, without the extra expense of heat recovery, these would be a good choice. Only one or two manufacturers make balanced ventilators without heat recovery. This type of heat-recovery ventilator provides balanced air flow and recovers up to 85 percent of the heat from outgoing air. By warming the incoming air, AAHXs provide greater comfort in cold climates than other types of ventilation systems.