Re: "In response to Robert Tangen-
There is no such thing as a "rectangular" or "tubular" frameless pack. The shape of the pack is entirely determined by what you put in it. FWIW The base of the pack is sewn rectangular." I BEG TO DIFFER, although I am no expert. I have the old MLD Revelation, which you seem to have copied exactly, except in Cuben fiber. Did you not read Ryan's comment that the pack fills out into the shape of a "log?" That's exactly what happens with the old Revelation, and what does NOT happen with the new one. The new pack has a wide, flat sheet of fabric in front and in back, and a narrow sheet of fabric on each side, with four seams providing a noticeable and effective structure, which the old pack does not have. (I can't speak to the ZPack, just the old Revelation.) Imagine a stuff sack for a shovel, shaped like the big pocket on most packs, but free floating: let's say the front panel is 18" square, as is the back panel, and the 2 side panels and the bottom panel are 2" by 18" are you saying the shape of that bag is totally determined by what's in it? I BEG TO DIFFER.