Named for the woman-specific double X chromosome DNA sequence, the Run XX NITRO running shoes stands behind PUMA's RUN FOR HER motto with a progressive, female-specific design. The running shoe features an updated fit that hugs a woman’s foot at the heel, instep, and arch, as well as a firmer NITRO midsole that provides cushioning over any distance. RUNGUIDE rounds things off by promoting proper alignment and increased stability.