"You don’t need to use the packing cubes, but I thought that as I was spending a fortune to import the bag, I might as well get a set of those while I was at it. I haven’t used them to capacity yet, but they are very useful for segregating and organising your gear and also making sure that you don’t over-pack. Since the packing cubes are sized carefully, you know that if your stuff fits in the packing cube, it will fit in the bag. This sounds trivial, but is actually quite reassuring for someone like me who has had some stressful moments in the morning before a flight anxiously sitting on a suitcase lid to wrestle the thing closed."
Read the full post @ but she's a girl... See also: the Tri-Star and Packing Cubes