I ride an assortment of bikes so a small bright taillight that is easy to rotate without having to undo a bracket appeals to me. The NightRider Sabre series lights are small and easily hung on a seat bag and bright enough for daytime use. If I have a seat bag without a light hanging tab, a safety pin will work too as you see below. I have a couple of Cygolite's that can hang as well, but the thin size of the NR makes these easy to use and thin enough to keep a back-up in the bag in case one runs down. At $30, the price is also an appeal.