Just finished 1st week with this fin, seems great does what its intended to do, did a 2 mile open water swim in calm conditions and have to say it was the easiest 2 mile swim ever. Just kept telling myself to slow down and lengthen the kick. These fins work great on the surface and did several hours of shallow dives to 20 meters, again this fin worked great, makes the decent effortless. It seems the slower your kick the faster they propel you.