This Trunk bag worked great on my 181-mile solo, single-day, unsupported trek down the C&O Canal Towpath (from Cumberland Maryland to Washington DC). It attaches securely with plenty of heavy velcro straps. I carried most of gear, tools, spares and food in the top part. The best feature is the collapsible panniers. I started the trip in the sub-freezing dark, with all my cold weather gear, and the panniers folded up and out of the way in their sleek zippered compartment. As the sun came up and temps climbed into the 50's, I was able to shed clothing, gloves, hats, etc. and load up the panniers. They hold a LOT of gear. You can even stash a certain amount of gear in the side pockets with the panniers folded up.I am not sure if this trunk is the best choice for heavy bulky loads or long-term trekking. I suspect there are more sturdy (expensive) choices for that. But for the rider who wants a trunk, and periodically needs panniers, this is a great product. Build quality seems good for these purposes - again, you might find heavier fabric and stronger mounting frames in true pannier separates. For the money and my purposes, this combo Trunk bag is great.