What's this weird blue 8-long thin hinge piece? I've spent several hours on BrickLink now trying to identify this mystery piece. It doesn't have a part number on it, only the Lego logo. It looks kind of like a hinge or something that might snap into a doorway, but I haven't found anything similar. Can you help me?
This is part 4218 Garage Roller Door Section without Handle:



As you might imagine from the name, these can be connected and used for garage doors as seen in Century Skyway, for example: