This file is for a dump truck and transfer trailer set, based on the older 'likens' style boxes. The print includes the trailer, both the dump and transfer box with movable tailgates, the frame to go on the truck you intend to use it on, and two hydraulic cylinders. The dump body will raise and lower, and can be positioned either up or down, depending on which cylinder you use. I have checked this file in a few different software programs, so it should print in the White strong polished material. Should there be a problem, contact me via the shapeway designer link, or directly via email to modelmechanic@gmail.com