BAKFlip MX4 448337 fits the 2021-2027 Ford F-150 with the 6'7" bed. Fold it against the cab and strap it down to drive with the bed open; BAK notes the 3rd brake light stays visible in every position. For the install, it clamps to the bed rails with no drilling; BAK rates it at 30 minutes or less. BAK's own brands list the box at 78.9". Revised EPDM perimeter seals and tight-fit clamps help keep weather out, and drain tubes carry off water that reaches the rails. BAK calls the MX4 America's best-selling truck bed cover, and the Gen 3 version adds re-engineered locks and a longer dual-action tailgate seal. It carries BAK's 5-year limited warranty.