New Balance Women's WR8508 Running Shoe 100% Mesh and synthetic NB ZIP is strategically located struts engineered between top and bottom plates, formulated for optimal cushioning, responsiveness and durability ACTEVA LITE is 24% lighter than standard midsole foam with Dupont Elvaloy and Dupont Engage for optimal compression set properties ABZORB SBS is an engineered, non-cellular elastomer designed to provide optimal shock absorption and no compression set Ndurance is a rubber compound for maximum durability used in high wear areas