Once the finger is glued in place (I use black and white of epoxy glue that sets overnight) I cut off the top of it that extends beyond the height of the plastic parts located around the ring. Here you can also see (on the right) the small latch that limits the travel of this ring to f/2 and f/32. When replacing the ring on the lens body this latch must be pushed in under the flange otherwise the ring will not mate with its counterpart below.