I ordered the "Medium" size, which is the biggest size. I stash this in my center-rear jersey pocket, and place the rest of my small repair kit in a bottle-cage-case. I can fit two road bike inner tubes and a Lezyne tire lever in the Caddy Sack and still be able to close the Velcro closure. For MTB riding, you can fit ONE inner tube and a lever, and that's if you fold it properly. It really is nothing more than a "simple" stowing bag - which is how it is described by Lezyne.