They teleport you to any location. Mario and Luigi went down one to get inside Meegee's house. Harry used this to block the basement door to lock Keitel, and to throw down a Bowling Ball. They come in all different colors sometimes too. There are also different colors of these things. They all do the same thing still. However it seems Red and Blue are very common as being very long. A lot of these are used in Peach's Castle as walls.