Needed to mount a generic spring loaded pull-up projector screen to a wooden beam from the front part of the screen.
Built in mounting options only allowed mounting to the ceiling, or to a wall on the back side of the screen.
These end caps replace the built-in endcaps, end modifies the mounting holes - leaving the option to mount to a wall from the front.
Installing the new endcaps requires re-tensioning the screen (as removing the old ones releases the tension) - a quick google search shows how to do this
The author hasn't provided the model origin yet.