On a Bitzenburger, the indexers have three possible positions, which you select by tightening and loosening the allen set screws mentioned above. I don't know if the left wing indexers are different from the right wing ones, since I only use left wing, but I do know that there are many different indexers available, of which I have a few. There are also indexers with blank rows that haven't been drilled, that you can drill to suit your own preference. It is very easy to lose the tiny springs and ball bearings in the indexer holes, so be warned.