A Zoom Air unit in the forefoot offers responsive cushioning. Every step helps create energy return to help drive you forward. It combines with a foam midsole for a firm, yet smooth and stable feeling as your foot hits the ground. Data from hundreds of runners helped inform the crash pad placement at the heel. It helps provide extra cushioning for heel-to-toe transitions. That info was also used to put cooling exactly where you need it on the upper. The durable rubber sole is built for mileage. Grooves in the forefoot to create flexibility, and vertical grooves down the side help create stability. Mesh is engineered for durability. Laces cinch down for a secure feel. A softer and more durable lining around the heel and ankle helps keep socks from bunching up when you run. Cushy tongue provides helps pad the laces. Molded heel securely hugs your foot.