it is good for foundation and paper piecing as well as the old But is also used when string quilting when you have irregular edges that should be cut evenly. If your supply list recommended it then I would urge you to get it. It will make the project easier to do as you don't have to continually sight the 1/4" seam. It is one of those things that you have to figure out other uses for it. Classes are much more pleasant and less stressful if you have the correct supplies.