These fins are fast! Let there be no doubt about that. I bought a large set and these are faster than the usual quad set I use (Rusty RPs) though they don't have the smooth tight arc feeling of the Rusty quads. It's a little more of a release and pivot feel but I haven't had too many good surfs on them yet. I'm using them in an HS Holy Grail. I also tried a small centre fin which didn't seem to make that much difference it felt marginally looser but I might be imagining it. Either way they deliver everything they promise - control at speed.