PUMA Women's Mobium Ride Running Shoe 100% Synthetic Imported MOBIUM BAND 2D - An elasticized band fused to a stretch TPU equates to 2 degrees of stretch. This band runs from the lateral heel to the medial forefoot and compliments the natural pronation a runner has. From heel strike to toe-off the Mobium Band allows for natural propulsion. It works dynamically just like your foots tendons: the more force that is applied to it, the more spring it returns; EXPANSION PODS - provide targeted flexibility, and are designed to align closely with the foots bone structure so that it flexes at exactly the same place and in the same way that your foot does; Synthetic sole Breathable mesh upper Mobium band provides two degrees of stretch and compliments natural runner pronation Expansion pods provide targeted flexibility