The MMG Canoe Pack is as Rat describes, a 15 or 30 liter roll-top closure 200 denier nylon water resistant stuff sack, with the same PALS attached belt and shoulder straps as on the Molly Mac Pack, and general purpose PALS array on the sides. It's modular, and we call it a Canoe Pack because that's what it most resembles.
You can put Molly Pouches on either side, to add volume incrementally with 1L or 4L pouches. You can remove the belt and use it as a lumbar pack, with Molly Pouches attached, as we did this last weekend in Linville Gorge.
You can also attach your Canoe Pack as a Molly Pouch to your Molly Mac Pack!
"We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin