Dee Zee Hex Series Universal Cross Rail Model DZ99799TBDee Zee Hex Series Universal Cross Rail Model DZ99799TB Dee Zee Hex Series Cross Bars Adds unlimited functionality to the Hex Series Side Rails (sold separately). Made of extruded hexagonal aluminum, the cross bars can slide forward and back independently on the side rails by hand loosening knobs. Channels allow you to ustomize the mounting of accessories anywhere along the chann el such as lights, tie downs, mountain bikes or tents (not included).