Adjusting objectives set

For sale is set of 6 adjusting objectives. I don't know how exactly they should be used, unfortunately. Seems to be rare and very special items. Below are few pictures to show you what is seen with each objective.
Also, there are three of them having same crosshair pattern. But each of them is for different tube length - 160mm, 190mm and infinity. All other objectives seems to be for 160mm tube.