With 3mm thick Aerospring(TM) foam and flexible heel cradle, Superfeet FLEXthin insoles offer long-lasting comfort for tight-fitting footwear. The Superfeet FLEX series of insoles offer an excellent introduction to the Superfeet experience.Features:Durable ConstructionAerospring Comfort FoamMoisturewick with Long Lasting Odor ControlDynamic ShapeFlexible Heel CradleVentilated ForefootBeveled EdgePlease keep in mind, for sanitation reasons, we can no longer accept returns for any used Insoles. Chat with one of our Gear Experts if you have any specific sizing concerns pre-purchase.