I ordered this
sissy bar bag for my first road trip on my bike. It has plenty of room with the roll bag (we women need as much space as we can get) I was able to pack a weeks worth. With all the extra straps it came with, it mounted and stayed secure on my bike.
The only complaints I had was the backpack straps broke after I packed it and went to move it. I had a local upolstory shop fix it for me and reenforce the other side of the strap( thankfully I had time before the trip). Then while away and only wanting to slide the bag out of the way without lifting it.
All in all the bag worked great for my trip and I hope to get plenty of more use out of it in the future. Barring anymore strap issues.