Altra's Instinct 3. 5 Men's Running Shoe is an attempt to improve what humans have been doing for hundreds of thousands of years: running. Our physiology has evolved to make running pretty damn efficient, so instead of trying to reconfigure something that already works, Altra designed the Instinct to help maximize the advantages we already have. Zero Drop technology encourages a natural, efficient, and repeatable stride, while the neutral support is designed for runners who already have solid form and are looking for a little reinforcement, rather than a large stride redesign. By allowing your toes to spread out, the FootShape toe box improves stability and power, and the A Bound recycled midsole returns energy from every step to propel you forward, saving you energy that you can use to run further and faster. Dual layer EVA foam and a Contour footbed provide extra support for ultras and marathons. Altra designed the FootPod outsole to mirror and support your bones and tendons, increasing comfort and reducing the likelihood of overuse injuries.