The bag under the seat has become an almost ubiquitous bicycle accessory, and there seem to be 1 million different options. After several attempts, I chose this because it was cheap, large, and had a quick release clip. I've been using Topeak bags for years, and I really appreciate its convenience because I can quickly take it out and switch it to another bike, or take it with me when I park somewhere. Surprisingly, the Coolchange package is more spacious than I expected, but not clumsy. It is longer, not wider, which makes it undisturbed. I also like the hardness of this material so that it doesn't wobble like some soft bags. My only two drawbacks are the side zipper, which requires two hands to open / close because of the angular shape of the bag, and the soft plastic connector under the seat. As you can see in my close-up, it bends under the tension of the bolt. Neither of these questions is an obstacle to trading for me, because this thing is less than $20, which is much better than some other things. I've put about 40 miles on this bag, and so far, it's good on the road and on the path.