Bilstein SA4 Series Shock Absorbers are designed specifically with custom street rods in mind using Bilstein's patented gas pressure technology. These 46mm monotube shocks are hand built to insure that top level quality is achieved with every shock that goes out the door. Each shock is tuned digressively using Bilstein's proven deflective disc valving technology and are available in two off the shelf settings as well as a custom setting. The show polished, billet aluminum body encourages rapid heat dissipation while saving on overall weight of the vehicle. The internal bore has been hard anodized to minimize wear caused by friction making these shocks extremely durable. The 5/8" polyurethane bushing mounts have been impregnated with graphite, virtually eliminating the squeaking commonly associated with polyurethane, and are used top and bottom to promote a long life.