Named for the woman-specific double X chromosome DNA sequence, the Run XX NITRO stands behind PUMA’s RUN FOR HER motto with a progressive, female-specific design. Featuring an updated fit that hugs a woman’s foot at the heel, instep, and arch, the running shoe’s new, firmer durometer NITRO™ foam midsole is the perfect balance of durable and lightweight. RUNGUIDE promotes proper alignment and increased stability for longer distances.