Full air cushion beneath my feet, internal support for arches. When I walk, the natural motion of the foot has the effect of giving the bottoms of my feet a massage as the internal air bladder pressure varies (think what happens when you step on a balloon or air mattress). Pricey in comparison to other shoes, but the premium above other shoes is maybe 2 deductible payments for my monthly Lyrica Rx... so an easy call for me. CB