US sizing Stable and arch supported for overpronation, the Guide 18 is a touch softer to wear than most arch supported runners. The support structure is not an old-fashioned wedge, but a comb that allows the shoe to flex in a natural fashion. The updated model has a thicker sole structure than before, and its Center Path technology combines stability, a nimble feel and great response: your foot is not just lying on a slab of foam, the sides turn to follow and support the sides of your feet. - PWRRUN mid sole foam for a softer feel than most EVA foams - Hollow Tech TPU structure under the arch for support - 3D-engineered fascia in the upper - FORMFIT structure enables a fantastic fit around the whole foot - Excellent heel fit - Heel stack 35 mm, front stack 29 mm, drop 6 mm