The ruler is actually called the X-block ruler and comes in different sizes, like 6.5 inch and 7.5 inch. By using this ruler you can make 9 patches, put the ruler on top of the 9-patch and then cut at wonky angles. The ruler comes with a few patterns telling you how to use it, but my guild used a "Topsy-Twosy" pattern by Patricia Pepe of Quilt Queen Designs. The ruler comes from Quilt Queen Designs also. Can get some really interesting patterns using this ruler. If I can figure out how to post photos I will post of my two quilts- one throw size and one more of wall size hanging. It was great fun and made me feel really creative since fabric choice made all the difference in the world in how everyone's top looked.