The "Doubles" file has 2 double panel frames. One has a connector tab to add more double frames or a single frame. The second double frame has no connector frame and would be used as a 2 panel card. The "Singles" file has 2 single panel frames. One has a connector tab to connect to subsequent frames. The second single frame has no connector tabs and would be used as the last frame in a series. Various mats are included in both files.
There are score lines (green) for the main folds. Other score lines (magenta) are located at the top(s) and bottom(s) of the inner panels. I do not use the panel (magenta) score lines as they seem to weaken the structure. That panels easily fold without them.