The Nano X4 training shoes are one of the lightest and most breathable versions of Nano to date. They are designed with an emphasis on stability and support, without excessive design features that add weight. The updated upper made of woven Flexweave is extremely lightweight and a new ventilation panel in the midfoot allows for greater airflow. Ultimate stability comes from the innovative Lift and Run Chassis system. Details: upper made of flexweave® with TPU heel clip midfoot ventilation lace-up closure floatride energy foam cushioning rubber outsole 7 mm black-grey