The bars that the fabric is rolled on, I can't remember the technical term. They are very flexible and when I roll the fabric forward they pull in in the middle and my quilting is not straight. If I could find stronger bars, I think it would be much better. Very frustrating to have uneven quilting. I bought this from a quilt store and they refused to help me set it up so maybe I have done something wrong. Anyway it is no fun to quilt on. I went to a local quilt store and they told me the only thing to do was buy a different quilt frame. I can't spend another $2,000. Thank you for your response. Linda G.