Brooks - The all new Brooks Adrenaline GTS 21 running shoe features extended DNA LOFT plus Guide Rails support making it a surefire recipe for comfort that's custom made for your stride. Smooth transition DNA LOFT goes beyond the heel all the way to the forefoot for a buttery smooth stride. Guide Rails holistic support system Brooks have shifted their focus beyond the feet to the most injury prone part of a runners body the knees. Guide Rails support keeps you moving comfortably by keeping excess movement in check. Soft secure fit The new Engineered Air Mesh upper hugs the foot for a secure fit while also improving breathability. Stretch structure The 3D Fit Print applies strategic stretch and structure to the upper. This shoe is a D width.