It will fit a 6-7 inch wrist nicely, if you have a smaller wrist you can use a smaller cord.
You can also use this to keep any cords or wires from tangling (steps 1-8) it also shortens it to about 4th of it's original size.
Step 1: The chain knot
To begin make a small loop near one of the USB heads.
You should have a loop coming out of the old loop.
Repeat this about 8-9 more times and move to next step.
Remember, as it goes on you'll keep making arches and putting them through the loops. You'll pretty much be repeating steps 1-7.
Put the opposite head through the loosened end.