The name of the ruler is Westalee Adjustable Ruler.
I hope to find one at nancy's notions. If you google that name, she has a video on how to use it and what surprised me is the copyright of the video is dated 2009.
I wonder why we haven't heard more about this ruler, it's time to take a ride to Beaver Dam to find out if it is still available. Heard it is expensive.
Carol J.