New Balance Men's MX8518 Training Shoe 100% Synthetic and mesh NB ZIP is strategically located struts engineered between top and bottom plates, formulated for optimal cushioning, responsiveness and durability NB ZIP heel utilizes 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 outsole and tip utilizes a rubber compound for maximum durability used in high wear areas