With a 3D printed sole that has my heart, the Grit offers resistance training by mimicking the feeling of standing/running on sand. The soles come with an interwoven pattern that collapses gently under pressure, just like how your foot sinks into the sand. Wearing the Grit allows you to exercise more efficiently, and build muscles by battling the resistance!
They are number 6 on the list here. I would wear them even if I am probably too old to get away with such a design.