Monroe 37191 OESpectrum Sensa-Trac Light Truck Shock Absorber All Weather Fluid: Contains special modifiers to reduce friction and ensure smooth rod reaction Full Displaced Valving: Valving automatically adjusts to road extremes to provide consistency and ride comfort 1-3/8" Bore: Larger bore than most shocks to provide more efficient and consistent control Fluon Banded Piston: Works with the existing groove tube technology to provide responsiveness to changing road conditions Unique Groove Tube - PSD: Precision tapered grooves in the pressure tube perform like an additional stage of valving for optimum light truck ride tuning