Bilstein CA4 Series shock absorbers are designed specifically for custom street rod applications that require unique lengths and valve settings for the proper chassis setup. Built around a billet aluminum monotube design, these shock absorbers feature a 46mm piston, threaded body, 5/8 inch polyurethane bushing mounts and various lengths and valve settings to choose from. Each shock absorber is supplied with a hard anodized spring seat, lock ring, and hat to accommodate a 2.5 inch ID spring. Bilstein CA4 Series shock absorbers provide a wide range of options to support any custom street rod application need.