Patented a few years ago by Hobie!

The fins reverse for reversing propulsion and fold up/back on impact to reduce damage when striking underwater obstructions. Read the full abstract. I can't tell if the socket might be similar if not the same.

It appears there is a short lever at the base of the drive that you lift or pull to reverse thrust.

I don't really find myself wishing I had a reverse often, but it would be nice to totally stash the paddle for emergencies ..
Phill Pittman new website for product development Best kayak source in Texas REAL wooden lures