Often you may find a screen that has been wrapped around the top of a vent. This is the classic way to protect a vent. However, two issues with this. First, the screen has to be extended all the way down to the base. This is often not done, in fact the commercial screens available only cover the top. Squirrels will chew the sides if they cant get to the top, and you end up with a pretty bad leak, especially if its on the upside of the vent. The other problem is that this doesn’t repair a vent that’s chewed, so putting a screen on a chewed vent is akin to closing the barn door after the cows are out. Critter Quitters will repair and protect the entire vent, plus the look a heck of a lot better than a screen. Critterquitter.com. Amazon or homedepot.com