Here is a review on Home Depot.com from a couple selling their house and they needed to have their vents repaired quickly. Roofers were charging way too much and shingle damage from having to remove them was a possibility, so they chose to use Critter Quitters. We are having more and more people starting to use Critter Quitters for this purpose, repairing a vent prior to inspection. Its inexpensive and effective.
Here is the review. We hope to be in the Home Depot stores someday.

Our squirrel problem is a thing of the past now, hooray! This is a perfect way to take care of the chewing of our pipes on our roof! So glad this product is made (and in America!) but do wish they carried them in the stores. We found out we needed two additional Critter Quitters after installing the first one so it would have been nice to just go purchase them at the store. Home Depot should definitely look into carrying them “in store” as I’m sure other people have this same issue and don’t know this product is available without a lot of searching.

Pros: Easy to Install, Easy to Use, Economical, Performs Well, Seals Well