The Bilstein SZ Series digressive valve 2 in. steel body shocks are designed for but is not limited to asphalt and dirt late models, Modifieds, IMCA-type Modifieds and Stock Car/Hobby Stock. Bilstein's industry-leading, digressive-valve technology features 46mm (1.81") diameter steel, sealed monotube gas pressure shock, Linear style valving, converts to coilover applications, plated for durability and rapid heat dissipation and Bilstein's famous consistent, fade-free performance.