Reflectivity: Contains reflective materials designed to enhance visibility during low light hours. I.G.S (Impact Guidance System) Technology: ASICS design philosophy that employs linked componentry to enhance the foot's natural gait from heel strike to toe-off. Fluid Ride Midsole: Fluid Ride provides the ultimate combination of bounce back and cushioning properties with reduced weight and exceptional durability. Heel Clutching System Technology: Exoskeletal heel counter provides improved support and creates improved heel fitting environment.