The new women's Adrenaline GTS 21 features extended DNA LOFT plus GuideRails® support — a surefire recipe for comfort that's custom made for your stride.  DNA LOFT goes beyond the heel, all the way to the forefoot, for a buttery smooth stride.  We’ve shifted our focus beyond the feet to the most injury-prone part of a runner’s body: the knees. GuideRails® support keeps you moving comfortably by keeping excess movement in check.  The new Engineered Air Mesh upper hugs the foot for a secure fit while also improving breathability.  The 3D Fit Print applies strategic stretch and structure to the upper