Loading, Please Wait... RunFlex Type  Sport Shoe Selection  Athletic footwear/high performance running shoes. Control Option  2 mm, 3 mm, 3.5 mm Length and Standard Cover   Full Length Blue ETC Patient Selection  Specially engineered for the high performance runner. Special Features  Extrinsic rearfoot flexpost (with a Lunasoft™ layer) to relieve Achilles' tendon strain, vinyl sandwich for topcover stability.