Machined from a solid block of aluminum, these cover plates feature heat sinks that help reduce oil temperature within the geared hub, extending the life of the oil and bearings. This easy upgrade provides a huge advantage when under heavy loads, towing, or high-performance applications. The PPE Heavy-Duty Billet Aluminum Geared Hub Covers also feature a high-powered Neodymium magnet-equipped service plug that helps to attract and hold harmful ferrous metal contaminants. 1992-2006 Hummer H1 Heavy-Duty Billet Aluminum Geared Hub Kit Black