I think they are called Zero rings (Brand name Zero not a reference to a type)
Most of the time you will need a lapping bar to make sure they do not twist the scope. In all honesty, they were never expensive rings and probably better off being replaced. In saying that, I used some to mount a spotlight on a scope many years ago when cables and halogen was a thing..... Removed the bolt from one side, replaced it with a bolt that was about 1" too long that had a wing nut fitted before attaching it to the ring. That way I could tighten or loosen it by hand and the wing nut was captive so it did not get lost in the field....
Simplest way is to clearly mark the centre of the ring, and mark the centre of the base you are attaching it to. Then make sure those marks line up and put it on the rifle without the scope. Then use the lapping bar (or any on inch tube to push through the first ring and make sure it lines up with the other ring. Height should be sweet, but you may need to move a ring left or right to let the bar line up. Ones lined up tighten them carefully and check they have not moved using the bar to make sure they still line up. Once that is done, at that point you can fit the scope. But I would bever use an expensive scope in these type of rings, if something works loose and is not tightened correctly it can easily twist or damage the scope. As mentioned, the best solution is not to use those.
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