The vent this is supposed to be a direct replacement for Ventline and requires a 360 degree knurled knob for the vent open/close mechanism to attach properly. My original vent gear was keyed instead of knurled. As in, it was a round shaft with a flat spot on one side. In my case I was able to 'steal' a different vent opening mechanism from a different vent cover that did not have an original cheapo fan in it. The Vortex seems to move quite a bit of air. I put mine in the main living area and it is a bit louder than expected but not a big deal unless trying to watch TV. Will likely install another in the garage so I can use it to cut the noise (use it when watching TV). Also planning to add a DPDT switch on the wall so I can choose whether the air comes in the roof vent or goes out it Since I can't reach it without a 'grabber' I picked up at harbor freight for $2. The grabber allows me to open/close the vent and push the button without a step.
