My flute case doesn't have anywhere to store the cleaning rod, so I initially bought this is a simple way of being able to keep the cleaning rod inside the flute yet stop it banging around and damaging the inside.
But this swab comes with a trick up its sleeve. It has a cap that you put on the end of the cleaning rod so that when you put the swab over the rod, the cap forms the swab into a cylinder shape the same size as the inside of the flute. That way, when you move the rod (and swab) down the inside of the flute, it cleans the whole diameter of the flute.
Neat!