Extang Tool Box Tonno Truck Bed Tonneau Cover | 32940 | fits Chevy/GMC Silverado/Sierra (6 1/2 ft) 99-06, 07 Classic (incl HD) L-Channel Rail Bridges the Toolbox-To-Tonneau Gap For Perfect Fit L-Channel Rail also provides a seal against the box Toolbox Tonneaus Fit Most Standard Size Toolboxes, 18-20" Exclusive And Patented All-Climate Tarp Design Adjustable Snaps and Bows For Easy Use In Cold Weather