Eagle Creek Pack-It™ Specter Cube Set.  This is a set of 3 cubes.

Ultra-lightweight packing organization. Three silnylon cubes that weigh less than 2.2oz cumulatively, means you can keep your clothing organized without worrying about weight. This translucent fabric is the same fabric used for lightweight tents and backpacks, it is super-durable, stain and water-resistant. Provide customization and space savings for any backpack, day bag or piece of luggage.
If you can roll it, these travel cubes can hold it. Cube, Half Cube and Quarter Cube

http://shop.eaglecreek.com/packit-specter-cube-set/d/1229