They won't scratch other templates and rulers, the way sandpaper can. They are ultra-thin, so they keep the ruler close to the fabric, unlike other products (this means more accurate cutting). And, you can slide the ruler around on the fabric until you get it perfectly aligned. When you apply a little pressure to hold the ruler, the SlipNotsTM really keep it steady. Hint: instead of cutting squares, use a 1/4" paper punch to cut dots from the SlipNotTMmaterial. The round dots adhere to the ruler better and stay on better. To insure the best adhesion, use a pin to help you remove the backing paper. Recommended by Omnigrid. Each package contains 3" by 3" square of self-adhesive SlipNotTM material.