A BIOMORPHIC FIT™ upper uses technology to give you a better fit and improved comfort, while the I.G.S™ (Impact Guidance System) technology helps your feet perform in a way that enhances natural gait. Great cushioning gives walking-on-air comfort, and this shoe has it in spades thanks to discreet GEL™ technology in the heel. There's also TRUSSTIC SYSTEM™ technology, a moulded part under the middle of the foot that provides stability.