I love boh my 12" and my 18" but I use the 18" more. What has helped me to avoid shifting are two huge clamps that DH got me from Lowe's. They have red plastic on the squeeze handles. I mostly use one but sometimes both. My cutting table fortunately has an overhang so they clamp the ruler easily. They absolutely stop any shifting as they grip super hard. I also have the accuquilt GO but I almost never use it to cut strips anymore.