Hiltex 50604 10" Coil Spring Compressors | Hardened, Heat-Treated Steel | Strut, Auto Suspension Remover and Installer Kit Permits quick and safe removal or installation of springs while repairing struts; Minimum tensile strength of bolts and 105,000 PSI Bolts are made with a hardened and tempered, precision-machined steel with a black oxide finish that prevents corrosion and rust. Compressor jaws are made with drop forged, heat treated steel with chrome plating for high strength and durability Compressors are designed to maintain and preserve spring curvature while compressing Compressors fit most strut sizes on domestic and import vehicles and can be used on other types of strut springs