They can be found at some truck stops, some truck dealerships, on eBay from time to time, or you can go to their
website to get a dealer list.
You might want to also check out
Crossfires. They are similar to Cat's Eyes, except they have a braided steel hose (instead of the rubber one that Cat's Eyes use), and they will idicate
overinflation as well as underinflation (which the Cat's Eye doesn't do).