13 series twin shocks for off road applications are dampers only. PS springs can be mated for a customized ride. Perfect choice for that old off-roader in your garage. Shocks feature a cellular foam chamber that enables the shock to be run in any position with no loss of damping performance. Heavy-duty springs do not increase the manufacturers allowed gross vehicle weight. Spring rate variations are performance. and ride quality options only. 1/2 diameter, heat-treated, steel shaft, hard chromed and precision ground for durability. Double-walled construction and 5-position adjustable preload.