ASICS Women's Gel-Kayano 23 Running Shoe 100% FluidFit/Mesh Imported Rubber sole Mpact Guidance System (I.G.S) (Running) : ASICS design philosophy that employs linked componentry to enhance the foot's natural gait from heel strike to toe-off FluidRide: FluidRide provides the ultimate combination of bounce back and cushioning properties with reduced weight and exceptional durability FluidFit: ASICS FluidFit upper technology combines multi-directional stretch mesh with stretch reinforcements that adapt to the athlete's foot, creating a truly customized glove-like fit Heel Clutching SystemTechnology: Exoskeletal heel counter provides improved support and creates improved heel fitting environment..With improved fit, the new shape not only holds your heel better, it holds the entire foot better while providing superior toe spring. Rearfoot and Forefoot GEL Cushioning Systems: Attenuates shock during impact and toe-off phases, and allows movement on multiple planes as the foot transitions through the gait cycle