Müsste es nicht heißen "narrowing towards the tip"?
I copied this from the Zeus website. But a thinner profile towards the tip is definitly not new innovation. The Tribal fins Symspeed has 2 different profiles for a long time, at the base thick, a sudden change at 1/3 and than a thinner profle towards the tip. I used the tribal symspeed in 2017. This fin was not sensitive for spin out. Also a a Tectonics fins model has this feature