These anodized aluminum rails attach to the inside walls of the bed and feature adjustable cleats that slide along the rail system to secure cargo of various sizes. Accommodates the Sliding Toolboxes, Sport Utility Bars and Cargo Bed Divider (all sold separately). Roof Rack Crossbars and Side Rails are necessary for use with all Lifestyle Carriers. Crossbars and Side Rails slide and lock at several preset positions for customized cargo carrying.