Fitment Fits Chevrolet Avalanche & Cadillac Escalade & Chevrolet & GMC: (Suburban, Tahoe, Yukon, Denali) & Chevrolet / GMC 1500, 2500, 3500,Many Chevy and GMC Trucks 1998-Up. Material Precision milled from durable DuPont Delrin (an acetal resin), corrosion resistance and long-term reliability. Professionally manufactured to specification, meet or even exceed standard in function, performance and quality. Function Prevents front hub vacuum leaks that would cause the 4WD to not engage. Ensure the seal is installed properly and without damage both the axle shaft and the wheel knuckle. Package included .