The Brooks Glycerin GTS 21 provides you with miles and miles of softness and stability. This plush shoe is optimized for your comfort by being lightweight, responsive, durable and cushioned. Whether you are on your feet all day for work, enjoying a daily walk or training for a marathon, the Brooks Glycerin GTS 21 gives you a stable and plush experience. Brooks uses its GuideRail® technology to support your body in its natural motion path while keeping excess motion in check, ideal for those with flexible arches or who overpronate and like a bit of extra stability. Details Upper - A new, engineered warp knit upper improves the fit and feel on your foot. It is breathable and flexible, while still being soft and secure. Midsole - the new nitrogen-infused DNA LOFT v3 is added to the Glycerin GTS and there is even more of it to give you a plush, durable and responsive ride. A broad platform makes sure you have smooth heel-to-toe transitions.Stability - Brooks’ GuideRail® holistic support system supports your body in its natural motion path while keeping excess movement in check, similar to bumpers on a bowling alley.Outsole - New RoadTrack rubber on the outsole is lightweight, durable and includes recycled silica.