I've taken several workshops from Bonnie. She doesn't push the rulers, just says that is what she uses. The rulers are cheap and are basic rulers for cutting. I already had the rulers in my stash from years back. I had problems with my hsts not being big enough. Bonnie watched me cut and saw immediately what I was doing to cause that. I was not being exact in placing my ruler on the fabric. She cut several for me and they sewed up perfectly.