ACDelco 520-177 Advantage Gas Charged Rear Shock Absorber by ACDelco

Super-finished chromed piston rod inhibits corrosion and provides a more consistent wear surface;Piston seal adjusts as it wears to maintain a tight seal between the piston and pressure tube. This minimizes leak paths for a longer, more consistent, product life;O-ring provides constant pressure to the inner tube and makes the valve less susceptible to dirt, wear, and fatigue leading to longer service life;Drawn over mandrel (DOM) pressure cylinder for a smoother surface and less resistance, resulting in increased service life