Roll-N-Lock Corporation offers their retractable hard tonneau cover for the popular 2004 Chevy Silverado and GMC Sierra 1500 Crew Cab Short Box pickups. With the smallest housing dimension in the industry, the Roll-N-Lock design allows more room in tight short box areas. The lock is integrated into the latch mechanism, and when the cover is fully extended the latch engages both the tracksk and the tailgate.