While there's no shortage of pedestrian functions from these Invisible Shoes, I think it should be mentioned that these can be good for non-pedestrain functions. I found one I didn't expect.

 These have to be the BEST devises for push-ups ever! I mean, they grip the ground/floor perfectly without slipping [even better than barefoot in this regard] and,of course, one gets to feel the toes and arches participate  (strengthen?) in said push-ups rather than be paralyzed as in those enclosed deals.  Anyone else discover unexpected non-pedestrian functions?