Years ago I purchased a Lowe "Alpine Attack Summit." It is a 1800 cu in bag made of very lightweight nylon which is tough as all getout. The shoulder straps are mesh; they work very well for the loads I have loaded in this pack - up to twenty pounds.

It is extremely versatile. It is usually my carryon when flying; it is great for day hikes; on longer trips, it serves as a stuff sack for clothes and my sleeping bag and it is available as a second pack for whatever purpose. I carry it also when bike touring.

It folds up into a bundle about the size of my two doubled fists. I bought it about fifteen years ago - I am not sure if it is still in production. I have seen similar packs from other manufacturers. To me they make a lot of sense.