The Garvin Wilderness Track Racks were designed especially for fiberglass tops and vehicle applications that do not have O.E.M. factory racks. The track system incorporates two aluminum black powder coated strips, specially designed roof rack mounting brackets and all mounting hardware. The mounting tracks are included with rack. The Track Racks are available in either the Off Road Series(6"H) or Sport Series(4"H). Track racks are available for most vehicles. Download the Garvin Wilderness Track Racks application guide at our web site to check availability for your vehicle. Rack fits 1999-2006 Chevy Silverado, 48"W by 60"L, drilling required for installation.