<p><strong>INSTALLATION </strong></p><ul><li>Backdraft damper 4 installation is very easy and uncomplicated. The exhaust shutter can be installed either vertically or horizontally. If you are installing the hvac dampener horizontally make sure that the axis is perpendicular to the ground. This will avoid the flaps from hanging open. For vertical installation this isn't a problem</li><li>The air damper will be pushed into the duct behind the ventilator. The white stripe will create a seal around the damper. The black gummi band should be inserted with the 4 in damper into the duct as well as this reduces loud clapping noises from the 4 inch backdraft damper. </li><li>Backdraft preventer flaps needs to open with the flow of air from your bathroom fan. The dryer vent draft blocker if installed incorrectly can damage your ventilator therefore make sure the flaps open in the right direction, with the flow of air, going outside.  </li></ul><p><strong>GUARANTEE</strong></p><ul><li>4 inline damper is made to the highest quality standards and if your expectations are not met, we offer a full refund and a year long warranty. Please contact us if you have any problems, or questions. Customer satisfaction is very important to us.</li></ul>