This kind of rungs is suitable especially for training board Simple board. Actually you can use it on the Finger board as well but since there are more holes for screws then the variability is lower than potencial.

There are four holes (older version on the picture...). When it is applied on Simple board then you attach it through board directly into inside threads in the wall. When it is applied on Finger board then you attach it into holes with inside threads in the board.

Rungs are double sided. It means you have 2 in 1 (one rung with two grip possibilites) when you twist it by 180 degrees.