TYR RD-1X is equipped with the latest in foam technology, Surge NRG+ enhanced with supercritical foam for ultimate comfort, response and durable support. The lightweight upper provides unrivaled airflow and response with added anti-stain-treated engineered mesh to keep you feeling fresh. 10 mm heel-to-toe. These are so soft, squishy and comfortable to wear I tossed the box. They have 8 miles and one track session on them.