These packing cubes are fantastic!  If you are on a long trip living out of your suitcase, these are wonderful to have.  You don't have to mess up all your clothes when you have to dig out something to wear that is in the bottom of your suitcase.  Just pull out the cube you have it stored in, and return the cube back to your luggage.  I have bought 2 sets of these.  The initial set I bought was the large size and I loved them so much, I bought anther set.  This time the medium size.  The medium size if about half the size of the large.  I find the large set more useful when packing a large suitcase, and the medium size for packing a small carry-on.  My next purchase will be another large set, since 3 are not enough to fill my large suitcase.