WeatherTech (32U7807 UnderLiner Bed Liner, Black 2007-2017 SILVERADO/SIERRA 6.5 FT BED UNDERLINER BLACK Silverado Box Size: Standard Box (78.7  78.8) Part Number: 32U7807 WeatherTech UnderLiners are designed exclusively as a protective layer between the truck bed and an additional rigid Bed Liner. Do not use the UnderLiner without installing an additional rigid Bed Liner to secure it in place.