Langstroth Super Follower Board
Follower Boards look similar to a frame dummy board, but are sized a bit larger so they fit all the way to the ends and bottom of the hive box allowing you to limit the size of the super.
I ordered two Langstroth Super Dummy Boards for my Langstroth hives. They came in the post, I went to put them on my hives but they didn't fit. The board was way too wide.so had to cut them with a saw and then sand down.