Click on the thumbnails to see a larger image

In steel mills a big "C" or an upside down "U" type grabbing hook suspended from an overhead crane move the coils around.  The center area on each coil cover is for the hooks to grab. The four supports on the coil car covers are "rests."  There isn't always a lot of room in the yards where the coils are loaded or unloaded and before the coils can be loaded the covers must be removed.  Many times the covers will be stacked on top of each other and that is what the rest are for.

This is also why you see the hoods of different roads matched with different cars, as crane operators often don't bother refitting hoods back to the correct car.  (thanks E. Klepzig and B. McClung)