
Tried them without success.
The idea of them is to kick relatively straight legged from the hips and thighs, rather than from the knees and ankles(putting strain on the ankles).
I found that i couldn`t get that quick kick for the takeoff.
They were uncomfortable, hard to get on & off, one kept slipping around the side of my leg.
Only tried them twice before giving up and eventually giving them away.
Bought them new for $100.
If strain on the ankles is a problem, normal flippers can be trimmed down with sharp scissors.