Wow, I didn’t realize that not many people knew about them. A TW is a pouch that mounts on the hub of your front/back wheels that lies within the spokes. In it, it holds a spare tube. It is really nice because they don’t take up any space, don’t weigh much, and it is always nice to have a spare tube when your riding. I will try and find a picture and post one if I can. Apparently nobody knows. Is there any way that one of the Site Moderators would know about a TW?