When I first saw these I really could not understand what was so great about them and now I can only wish I had the patent on them because they are quite wonderful. It's kind of hard to say why these are so great except to say that your bag will never be so organized and easy to manage, as with these. Instead of taking every clothing item out to find something and then having to re-pack it all, you'll have these handy cubes to retrieve your items from and it keeps things so much neater. Usually, my suitcase is a mess once I open it and I am constantly repacking it and refolding things. But I've been using these for a year and a messy suitcase is for the most part, a thing of the past for me with these cubes. The cubes are breathable and durable. I use the smallest one for very small clothing items, the medium one for things like shorts, t-shirts & pajamas, and the large one for jeans, pants and dresses, or sweaters. It is just way easier to stay organized and on top of what you pack using these. They are not a "necessity" in life, but they have become one for me. It makes travel way more convenient and as long as I have them, I will use them for every trip and would replace them if something ever happened to them. I like them that much. I would be very surprised if anyone did not find them to be extremely convenient. Doesn't seem like you need them till you actually start using them then you don't know how you managed before you got them. Just keeps the suitcase or bag much more organized and increases the space you have in your bag.