I have been working to come up with something to wear on your feet that provides warmth, ankle support, grip, and superior impact protection for your foot and lower leg. This is where I'm at and I tested it yesterday in cold river water, all I can say is SHAZZAMMMM!! I wear 2mm neoprene socks inside as well, outer shell is approx. 10mil closed cell foam, and I added 2" velcro cinch straps for support. Provides all the above with decent flexibility and some feeling of that "bare foot" type of stance without a rubber shoe sole. Fills my Rev footholds perfect.