{The sole|The only|The only real} they developed is the patent pending microwobbleboard sole. {As the|Because the} foot {moves|strikes} {through|via|by way of|by means of|by} the {walk|stroll} cycle, the {lower|decrease} leg {muscles|muscle tissue|muscular tissues|muscle tissues|muscle mass|muscle groups} {must be|have to be|should be} used {more|extra} extensively to retain stability. {The final|The ultimate} product {became|turned|grew to become} the FitFlop sandal.}