ASICS Women's Gel-DS Trainer 21 Running Shoe 100% Textile and Synthetic Imported Rubber sole Shaft measures approximately 2.5" from arch 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. Rear foot and Forefoot GEL Cushioning Systems: Attenuates shock during impact and toe-off phases, and allows movement in multiple planes as the foot transitions through the gait cycle. Dynamic duomax Support System: This evolution of duomax system enhances stability and support, with reduced weight and increased platform support. Solyte Midsole Material: A lighter weight midsole compound than ASICS' standard EVA and speva. Also features enhanced cushioning and durability. Propulsion Truss tic: Mimics connective tissue in the foot by creating tension as foot enters propulsion stage.