Pick up the pace and set a record breaking win in the Brooks® Racer ST 5. An update to the Racer ST 4. Ideal racing flat for 5K to marathons. Open mesh upper optimizes breathability. Synthetic leather and microfiber overlays provide lightweight, targeted support. Element upper offers protection from the various elements in a lightweight, breathable fabric that is made to withstand even the toughest run. Contoured heel cup for added comfort and performance. Heel pull loop for easy on/off. Molded insole supplies lightweight plush. BioMoGo midsole provides long lasting cushioning and is environmentally friendly. A non-toxic, natural additive encourages anaerobic microbes to break it down as soon as it reaches the landfill. Fearfoot HydroFlow®, viscous fluid unit, enhances midsole cushioning and helps attenuate impacting shock. Diagonal Rollbar® (DRB) is a high-density post placed at the medial arch, designed to help with pronation control and create smoother transitions through the various phases of the gait cycle. DRB® Accel shank-like unit promotes torsional rigidity in the midfoot, while allowing the heel and forefoot to act independently. Engineered Stable Pod Construction helps set the foot into an efficient, neutral position throughout the gait cycle, promoting maximum stability. HPR Green is a long-lasting outsole compound made of dispersed silica, a more environmentally friendly compound. It offers excellent wet/dry traction and grip. Measurements: Weight: 10 ozProduct measurements were taken using size Men's 10, Women's 11.5, width Medium. Please note that measurements may vary by size.