**MISSING SOCK LINER. Must use your own insert/insole. Like-new condition. Used only once on the treadmill with my own insert. No box The Neo Zen introduces Enerzy NXT Nitrogen-Infused foam, giving your runs a distinctive bounce that keeps you energized and light on your feet. Paired with Smooth Speed Assist technology, this shoe gives you a buttery-smooth transition for every stride, so you can focus on finding your Zen.