Go Rhino Universal XRS 49 3/4 Cross Rail Accessory Set - Tex. BlackUpgrade your XRS Bed Cross Rail Kit with additional 4 CORE rails that bridge the uprights on both sides of your truck bed. 37 3 4 inch and 49 3 4 inch, although either can be cut down to desired length. The 4 CORE system is an extruded track system that works with any 1 4x20 hex bolt or Quick release clamps. Works with both mid size and full size XRS Bed Cross Rail Kits (5935000T 5935001T)