these are 12″ x 48″ x 30′ long Heavy Duty Crane Mats. Important points are flat top construction so that a Large Crawler Crane is not having to cross any “steps” in the mats. When the boom is up on some of these huge cranes we don’t want to see any dips or humps in the mats. A bump at ground level is a huge swing 120 feet in the air.