Jelly rolls are usually 2.5 inch strips of assorted fabrics that have 40 strips of fabric. I have bought several jelly rolls that have repeats of some fabrics in them, I now ask if there are 40 different fabrics. I personally will not make any jelly roll race quilts as I have books that are just fabulous using jelly rolls with a background fabric. I especially like Kim Brackett. I figure 20 strips is a half jelly roll.