For Nissan 350Z Performance Suspension Strut Damper with Coilover Complete Kit Z33 High quality CNC machined steel (Springs) and aluminum (shocks) construction Pillow ball upper mounts with rubber dust boot covers and dual locking spring perch applied Reversed Mono-shock and single-cylinder design Improved ride quality and handling Front spring rate: 9.00 kg/mm; Rear spring rate: 9.00 kg/mm