Call the shots when it comes to performance and comfort in the Brooks Glycerin GTS 21. Designed to thrive at any distance, these silhouettes let you go hard at it with max cushioning and even better responsiveness. The GuideRails holistic support technology helps you hit your stride on time and with stability, while the nitrogen-infused DNA LOFT v3 ensures endless cushioning. What's new? The RoadTack rubber that's made using a mix of rubber and recycled silica and adds more life to every mile. It's time to get serious about your running goals in the Brooks Glycerin GTS 21. Brooks Glycerin GTS 21 features: All-new engineered warp knit upper provides structure. GuideRails holistic support system supports natural motion while keeping excess movement in check. Stack height to 28:18 for a 10mm offset. 2mm of DNA LOFT v3 underfoot offers even more plush cushioning. Weight: 10.5 oz.