Yep. You need the ruler base.
Years ago I was talking with the folks from Quilters' Rule and they advised I only buy one ruler at a time. That way I could be sure I liked using them and then would be a more informed consumer of what I would want in the future. I couldn't believe they talked me out of a sale. They were right too! I only buy what I want. Of course, I know of a few LAer's and we can share if needed.