Nano X3 Womens 8.5 / Mens 7 Used but there is plenty of life left in these. VERSATILE FITNESS SHOES WITH A SUPPORTIVE BUILD Believe it or not, there's a training shoe you can actually run in. Meet the women's Reebok Nano X3 training shoes with the all new Lift and Run Chassis system. A dome-shaped heel piece compresses under load when lifting to create a stable platform, then softens when you push off to run. It all rides on award-winning Floatride Energy Foam that gives you lightweight cushioning to make that run the easiest part of the workout.