Fast R3 is the fastest running shoe we’ve ever made data back, lab tested, and built for breakthroughs. After testing it on elite runners and real athletes, we digitally engineered and optimized the product fully based on data. Fast R3 is designed to shave minutes off your race time. With its 3.15 percent improved running economy*, this translates to an unprecedented potential marathon time saving of more than 4 minutes and 30 seconds, for a 3 hour marathon runner. We cut 95g from its predecessor, stacked it higher with new and improved NITROFOAM ELITE, and extended the carbon PWRPLATE for maximum propulsion.