I used to draw crude numbers were I could fit them on my cables, to try and get some semblance of order in the mess that easily arise when recording many sources at once. Found this while searching for something better and decided to try it out.
Now all my cables are color-coded by length, and the small "label-area" on the ring allows me to have one clear place where the cable number can be written.
Have made setup before recording significantly easier, highly recommended.