This is a set of plastic blocks that will allow you to relocate the trucks for Micro Trains Z Scale 60' flat cars. The standard position of the trucks is too close to the end of the car. With these mounts, the trucks can be placed more toward the center of the car like the real thing. Body mounted couplers are required. There is a pilot hole on the flat car that shows where to drill and tap for body mounted couplers (flip through the images to see more details).