Smooth Performance: Polyurethane rebound bumper and bushings and graphite-filled fluon-banded piston help absorb ride harshness and enhance responsiveness to changing road conditions for an overall smoother ride Strong and Durable: Features an application-specific 18mm nitro-carburized piston rod to resist scuffs and corrosion, double-welded loops at stress areas and 1.25-in sintered iron piston for enhanced structural integrity Built to Last: Low-friction, self-lubricating seal retains gas and oil for quicker rebound and smoother compression while the long-lasting premium liquid metallic finish and polyvinyl protective boot ensures long life Industry First: Recognized as the first nine-position manually adjustable shock series in the off-road market Vehicle Compatibility: This Set of Rancho Front and Rear RS9000XL Series Suspension Shock Absorbers is compatible with 2002-2006 Avalanche 2500 & 2001-2010 Sierra 2500 HD (Torsion Bar); All models require 5-6" Lift This set includes 2 front and 2 rear RS9000XL series shocks. Recognized as the first nine-position manually adjustable ride control series in the off-road market, Rancho RS9000XL shocks deliver unprecedented control and performance. Ideal for on- and off-road use, towing and more, the adjustable damping enhances ride characteristics by counteracting the additional unsprung mass inherent in larger tire and wheel combinations. Low-friction, self-lubricating seal retains gas and oil for quicker rebound and smoother compression while the long-lasting premium liquid metallic finish and polyvinyl protective boot ensures longer life. Up to 2.75-in. tri-tube body (application specific) filled with all-weather fluid allows for cooler operation, increased vehicle control and ability to withstand internal temperatures of -40 to 248°F. Polyurethane bushings enhance performance and durability while a boot protects the shock rod and oil seal. Buy with confidence, the RS9000XL Series shocks come with Rancho's limited lifetime warranty. This set is compatible with 2002-2006 Avalanche 2500, 2001-2006 Silverado/Sierra 1500 HD (Torsion Bar) w/o Electronic Adjustable Suspension, 2007 Silverado/Sierra 1500 HD Classic (Torsion Bar) w/o Electronic Adjustable Suspension, 1999-2004 Silverado/Sierra 2500 4WD (Torsion Bar), 2007 Silverado/Sierra 2500 HD Classic (Torsion Bar), 2001-2010 Sierra 2500 HD (Torsion Bar), and 2003-2009 H2 (Torsion Bar). All models require 5-6" Lift