Have been looking at their site, and have pondered buying a set for a couple of years. Finally took the plunge, and installed a set over the weekend. I've been rotating and rebalancing my tires every 5000 miles or so and the last time was about 2 weeks ago. It's amazing how much smoother the ride is now, with them installed. I'm sure they will extend the life of my tires.
http://www.centramatic.com/
http://www.centramatic.com/