This ruler and the Wonder Cut Triangle companion ruler were developed by a mother and daughter in a small town in Idaho.
I have both the Wonder Cut & the Wonder Cut Triangle ruler, all of their books and all of their patterns. If you would like to visit their website:
http://www.wondercutruler.com
The website tells the whole story plus tutorials and many quilt pictures. I am not affiliated with the gals who developed this---just really like their products!