I shot thunderheads for years on aluminum arrows. I never could get them to fly right when I started shooting the newer graphite arrows. Now I shoot slick tricks and they fly great. I can tell you from experience with both that the ST are a lot tougher than the thunderheads. I’ve never bent a ferrule on the SL and to date haven’t bent a blade either. I did break a blade. They’re easy to sharpen, fly great and leave fantastic blood trails.