ASICS Women's Gel-Sendai 3 Running Shoe 100% Synthetic Imported Rubber sole Impact Guidance System (I.G.S): ASICS design philosophy that employs linked componentry to enhance the foot's natural gait from heel strike to toe-off. Fluid fit: ASICS fluid fit 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 System: Exoskeleton heel counter provides improved support and creates improved heel fitting environment. Discrete Eyelets: Independently placed eyelets disburse lace tension, creating a customized fitting environment and enhanced upper comfort. Discrete Heel Unit: Takes the Impact Guidance System (I.G.S.) to a new level by creating our highest degree of shock attenuation and stability.