ASICS Women's GT-2160 Trail Running Shoe 100% Synthetic and mesh Rubber sole Heel measures approximately 1 inches" 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. Guidance Line Vertical flex groove decouples the tooling along the line of progression for enhanced gait efficiency. Space Trusstic System