The most barefoot-like and lightest of the Free family, the Nike Free RN Flyknit 2017 Men's Running Shoe is ideal for short runs. A sock-like upper hugs your feet yet feels barely there, while an innovative sole lets your foot flex and expand naturally. And, their packable design is easy to stash in a tote or backpack—so you can pack in a few miles on the fly. Foot-Hugging Feel Flyknit material contours to the shape of your foot for a snug fit. Combining breathability throughout the top, support in the toe and stretch on the outside of the foot, the Flyknit material helps keep your foot cool during your run. Natural Movement The Nike Free sole provides the feel of a minimalist running shoe. It moves with you, mimicking the movement of your foot by expanding and contracting with every landing and push-off, for a natural feel. Ultralight Support Strong, yet feather-light Flywire cables work with the laces to provide more support as you tighten them. A set of cables has been removed from the top lace to allow for a smoother, less distracting feel when you bend at the forefoot. More Details Single seam on the inside of the heel for a smooth feel Rounded heel is made to roll with the ground as you stride Foam outsole with rubber at the toe and heel for durability Weight: 225 grams approx. (men's size 9) Offset: 8mm Nike Free Origins After learning that Stanford athletes had been training barefoot, 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 four 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.