Now with a vibrant new design, it will get you pumped to unleash your inner runner, even when it's grey outside. The GEL-NIMBUS® 21 shoe is fitted with our I.G.S® (Impact Guidance System) technology: a construction technique that allows the shoe to respond to your natural gait. TRUSSTIC SYSTEM® technology provides added stability. The upper is made from Jacquard mesh and will fit snugly, allowing air to flow and keep the foot fresh as you run and run. Our famous GEL® technology in the front and rear sole gives you energized cushioning in the form of shock-absorbing silicone for heavy-impact activity. Meanwhile, FLYTEFOAM® Propel technology in the midsole offers excellent bounce and toe-off. This lightweight foam formulation has a special high-energy return elastomer helping to put a spring in your step. Gain even more bounce with our SpEVA insole, which also helps the shoe last. To ensure a great fit, there's an external heel counter which holds your heel firmly, keeping you comfortable as you pound the miles. And we've added an AHARPLUS™ heel plug on the outsole to help you be able to run as long as you want. This ASICS High Abrasion Resistance Rubber is a tough rubber compound used to reduce excessive wear. All of this lets the shoe take the strain so you can concentrate on what matters: your breathing and pace.