This is a backpack from ORTLIEB. I purchased it about two years ago for around 40,000 yen. I believe the size is 25 liters, but I don't remember exactly (it holds about the same amount as a 30-liter backpack). I have used it, and there have been no problems like water getting inside. However, areas that often rub are showing wear, and the zippers are stiff, so I cannot guarantee waterproofness. There are places where the zipper doesn't close properly. See photo 9, where the zipper is slightly raised. Please check the condition of the product carefully before purchasing. The bag in the last photo (Wrangler Boston bag) will also be included as a set.