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
"Hello. I received my order promptly during the holiday season. It was correct and everything needed was included. Instructions were suitable. Installation was a breeze. I check them regularly and squirrels have yet to chew them which is much more than I can say for the standard lead flashing and more or less everything else on my roof or around my house. I haven't had occasion to remove them yet, so I can't yet say how that will go, but so far count me as 100% satisfied. A product that actually works as advertised is rare these days, but you've certainly done it here. Thanks for coming up with this idea and saving me lots of aggravation and expensive repair bills."
"If only keeping squirrels from chewing up my pool screen enclosure was so simple..."
T CMelbourne, FL
"Installed the replacement vent today, fits well, looks good."