Monroe 32304 Monro-Matic Plus Shock Absorber (Fits 4WD Model Only) 1/2 inch Diameter Piston Rod: Nitro carburized rod for long service life. On non-dust shield units only 1-3/16 inch Bore: Larger bore than most shocks to provide more efficient and consistent control All Weather Fluid: Contains special modifiers to reduce friction and ensure smooth rod reaction