They are the same as the grand prix 4 seasons as far as the kevlar belts, but seem to wear longer. BTW, I too think the ultra's are the way to go. I run 25C's with 120 psi rear and 115 front at 220 lbs and they ride super nice. No flats and I get lots of miles out of them. The armadillo's last a long time too, but I don't think they ride anywhere near as smooth as the conti's. The difference was quite noticable to me.