I was doing some free diving and long surface swiming in the lake. I swam about 2 miles probably in a couple hourse. Anyway, i own the jet fins and the rocket fins, and i love the power both those fins put out. So after we get back to shore, my buddy lets my try on his twin jets. Lets just say i've never felt so much relief. I dont know if ill purchase them because i want to get into tech diving, but i just want to say WOW.