Progressive Suspension PS-430-4402C 430 Series 12" Standard Spring Rate Rear Shock Absorbers Chrome for Street 15-20First of their kind, machined aluminum spring perches and street rod styling of the 430 Series are complimented by smooth lines and a polished chrome body. The 430 is a true value, budget priced but still feature High Pressure Gas Monotube and Deflective Disc Damping Technology. Available in 5 different lengths in Standard Heavy Duty Spring rates, fine tune the Preload by hand and hit the mean streets. Features High Pressure Gas Monotube Design