ACDelco GM Original Equipment Premium Monotube Shock Absorbers control the oscillation of the suspension and are GM-recommended replacements for your vehicle’s original components. A shock absorber is a hydraulic piston and cylinder that is designed to resist the up-and-down movement of the suspension. The piston has a valve or orifice that allows the piston to move up and down the cylinder tube at a controlled rate. The valving is tailored to the vehicle and suspension characteristics. These shocks feature the top-of-the-line single tube design with dual pistons that separate the nitrogen gas from the shock oil, providing excellent performance. These original equipment shock absorbers have been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.