Here is a picture of Critter Quitters available at the Winter Garden ACE located a 500 S Dillard St. They have a nice video playing that explains how they work. If you live in the area this is where to go to get them
"Yesterday, I installed the Critter Quitters® I purchased from you several weeks ago. The build quality is excellent, and the were very easy to install. Thanks very much for the phone call to assure they were the proper size. I an most happy with the result."
J OOrange, TX
"Product installed, working well and I am telling folks I know about them. A little pricey but a great product."