My bike (a Breezer) came with one. Can't be used for big/ heavy objects and I wouldn't use it on long or rough rides, but I've found that it comes in handy on a regular basis for holding small objects (such as mail going to post office) with minimal to-do. Not something that I would have gone out of my way to get, and I could certainly get by without it, but there have been plenty of times over the years when I've been glad I have it.