Shoes, for running as well as all other sports, are constantly being
remodeled to improve athlete's performances. Saucony claims to have
engineered a system that provides good shock absorption and lateral shoe
control. They call it GRID (Ground Reaction Inertia Device). GRID is
made of Hytrel elastomer, an interwoven system of shock absorbing strings that
bend to the shape of the heal. With the GRID system, runners receive both
cushioning and stability, resulting in a reduction of stress-induced
injuries.