The Brooks Adrenaline GTS 21 continues the trend of comfort and stability. The GTS 21 features DNA LOFT that runs beyond the heel all the way to the forefoot aiding in shock absorption and assisting in super smooth transitions. The holistic support system of GuideRails keeps you moving comfortably by keeping excess movement in check and allowing those smooth transitions from heel-strike to toe-off. The Engineered Air Mesh and 3D Print on the upper provides a hug and secure fit while improving breathability. Strategic 3D Fit Print for added stretch and structure to the upper. More DNA LOFT cushioning that extends throughout the midsole for a smoother transition from heel to toe. GuideRails support keeps you moving comfortably by keeping you excess movement in check. Engineered Air Mesh upper hugs the foot for a secure fit while improving breathability.