Celebrating 21 years as a staple in the neutral category, the GEL-NIMBUS 21 delivers the best ride yet. A new Flytefoam Propel middle delivers a sensational underfoot feeling of comfort and bounce. The double layer jacquard mesh upper provides a premium fit and more room in the toe area without sacrificing flex and support through the midst. This new upper adapts and protects the runners foot throughout the run. With new Flytefoam Lyte and Propel, the midsole creates a more plush / energetic ride in lighter weight package.