The GEL-Speedstar II is a lightweight performance trainer designed to meet the needs of the biomechanically effecient runner who wants a fast, flexible shoe with a comfortable, breathable upper. The GEL-Speedstar II features DuoSole Outsole for enhanced flexibility and durability. GEL Cushioning Systems for shock attenuation during impact phase and toe-off phases. Trusstic System links the rearfoot to the forefoot and shores the midfoot. SpEVA Midsole offers durability and shock attenuation.