Originally Posted by juneayerza

The sidelock is NOT meant to be used on top of another ruler. The ruler underneath can move because it will slide on top of the fabric. If you haven't watched this video, please do so, I think it will answer any questions you have. https://www.youtube.com/watch?v=hYOoRetnlfM By the way, I love these rulers and use them always; they are so much safer.