It's also called a prairie braid, if you want to look it up. Jelly rolls are great for these as if you use different widths, you will have to be adjusting constantly to keep your join points in the center. I generally use scraps, which are much more like work. I also use a paper or strip of old sheet foundation, which helps keep my work going straight. I am very fond of this pattern both for borders and between other long strips on a quilt, such as a border print or on-point 4 patches.