More sewing stuff

Singer ripper?, originally uploaded by foodchronicles.

In the organization process, I've also stumbled across a huge sewing filled, yes filled, to the brim with old sewing items. A ton of wooden spools of thread, more buttons, some vintage belt buckles and a few odd items.

One of them being the above. I have also taken a picture of it unfolded. Anyone have an idea of what it is and how it was used?