The Gel Cumulus 9 from Asics features Impact guidance system enhances the foots natural gait from heel strike to toe-off. Solyte Midsole Material which is lighter than the Asics standard EVA and spEVA. Space Trusstic System an advanced system that creates a pocket between the Trusstic System device and the midsole allowing for greater midsole deformation and a more efficient foot function. Personal Heel Fit memory foam lined heel collar molds to athletes heel creating a personalized fit.