I have two of these: one for the road bike and one for the mountain bike. The bag is big enough to stuff a tube, two 20g cartridges, an inflator, two tire levers, some spare quick links and a multi-tool in it. On the mountain bike, the tube comes out and I carry a tubeless plug tool. The bag snugs up nicely under the seat. .The only slightly dificiencies are: no hook for a rear light, and the zipper does not go back far enough on the sides. That doesn't limit functionality. I lke this bag, alot, and it comes in multiple colors, if that's your thing.
