I bought the 4.5L model on sale for under $45 at another site. For the money, it is a good value and it allows me to utilize the front water bottle cage on my mtn bike and road bike. The bag is well made but heavy, and it has a zipper on both sides, I'm not sure how useful this is. I also don't know yet how well it will perform on soggy, wet days. The mounting system does work perfect for my bike, utilizing the full length of the top bar. The 4.5L capacity is enough to hold extra water, tools, patch kit, and a few miscellaneous bits and pieces, as you may see fit. When bike packing, I plan to put my tent poles and some heavier kit in it. Overall, if my budget warranted, I would have probably gone with Ortlieb, as their bags are lighter and definitely waterproof, but for the amount of use I give them, this bag was easier to justify purchasing. Oh, yes, one other thing, I would recommend wrapping some clear tape over the contact points on the bike to avoid damage to the finish, goes the same for my Ortlieb bike packing gear.