Which ones they make a few of them. I just looked on Lancaster.
Natural feathers have two distinct surface differences which contribute to natural spin. Can a plastic vane do that?
These sound interesting, however, after ready the Ashby reports on fletching, I switched to 3” four fletch and water is not an issue. I’ve soaked them in water and shot them in rain and they fly fine. Granted, I don’t shoot much over 20 yards, but it works well. Check out Trad Lab on the Push podcast. There’s some interesting information.