FLEXIBLE, HIGHLY VISIBLE WEATHER PROTECTION.The Nike Free 5.0 Flash Men's Running Shoe combines a highly flexible, low-profile outsole for natural movement and the cushioning, traction and lightweight support of a traditional running shoe. The upper offers excellent visibility and weather protection to help you run in wet, dark conditions.Everyday FlexibilityNew hexagonal flex grooves are hot-knife cut into the outsole and wrap around the sidewall, allowing your foot to move more naturally in every direction.Weather Protection and VisibilityThe Flywire-reinforced mesh upper repels water to help keep feet dry while providing lightweight ventilation and an adaptive, supportive fit that moves with you. Allover reflectivity enhances visibility in low light.8mm OffsetWith an 8mm difference between heel and forefoot height, the Nike Free 5.0 offers the highest offset of Nike Free running shoes for greater cushioning with the foot-strengthening benefits of natural motion.More BenefitsTraditional tongue construction to cushion lace pressureMinimal sockliner molds to your foot's curvature for added support and comfortWaffle outsole lugs help absorb impact and add responsivenessWeight: 8.3 ounces (men's size 9)Nike Free OriginsAfter learning that Stanford athletes had been training barefoot on the university's golf course, three of Nike's most innovative and creative employees set out to develop a shoe that felt natural and weightless, similar to bare feet. In 2002, they examined a group of men and women with pressure measuring insoles taped to their feet, using high-speed cameras to capture images of each foot in motion.The team spent eight years studying the biomechanics of shoeless running. The results yielded a profound understanding of the foot's natural landing angle, pressure and toe position, allowing Nike designers to build an unconventional and flexible running shoe from the inside out. Since Nike Free's introduction, millions of runners have trained in the shoe, including some of Kenya's world-class runners.