Outfit your semi to be Ready for the Road Ahead with a smooth and reliable spring-operated door assembly, with the Diamond Roll Up Doors 7.1" Steel Roll Up Door Lock Assembly. This replacement lock assembly with a flat backplate makes it easy to quickly secure your load, and prevent the door from automatically rolling up on its own. Manufactured with corrosion and rust-resistant metals for extended use in harsh conditions and humid climates. FleetPride is your First Click in Heavy Duty .