NATURAL FEEL. POWERFUL STABILITY. The Nike Free TR Versatility Amp Men's Training Shoe gives you both lightweight lockdown and premium comfort thanks to Flywire cables and no-sew overlays on a breathable knit upper. A Nike Free midsole expands and contracts in every direction for the ultimate in natural flexibility. Benefits: • Warp-knit upper for breathable comfort and support • Flywire cables for a dynamic fit • No-sew overlays offer support and durability • Dual-density Nike Free midsole expands in every direction for natural movement • Reinforced rubber on the outsole for durability in high-wear areas Nike Free Origins After 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. The team spent eight years studying the biomechanics of runners' feet in motion. 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.