A musette bag is a lightweight shoulder bag, inside which food and drink are handed to road racers within the feed zone of a race. The bag is easily grabbed by the long strap handles, and temporarily placed over the shoulder. With skills as only the top riders can do, the food and water bottles are placed into the rider's rear jersey pockets and bottle cage.
If you are not a pro rider how will you use it?
Hang it up and use it to store arm warmers, spare lights, bike caps, bike computer, sunnies and all those little things that you grab on the way out the door: keeping them all accessible in one spot.