BAK 19-21 Chevy Silverado/GM Sierra Revolver X4s 5.10ft Bed Cover (New Body Style)Protect your valuable cargo with the RealTruck BAK(R) Revolver X4sthe best selling, most secure do it all hard roll up bed cover. Building on the proven Revolver platform, the X4s delivers upgraded materials, enhanced weather protection, and an all matte black finish for a stealthy, refined appearance. As the most secure hard roll up in its class, the Revolver X4s features patented rotational locking rails and automatic slam latches to prevent prying,