This is a telescoping way cover for the Z axis of the tilt-column Sieg X2 derived mini mill family. It should work on the solid column versions, but I don't have one so I can't test it.
The lowest/smallest cover anchors to the screws that attach the back Y axis cover to the column, and the top snaps to the head of the mill with ½"x1/8" round magnets.
If you're still using the stock wound-spring Z lift assist, this will probably interfere.
The author marked this model as their own original creation.