Very much necessary when packing for your trips. The cubes are very durable and hold a lot. In the picture, I have the extra large and a large. Inside the extra large, I have the small cube with all my toiletries. I also have 3 pairs of jeggings, 2 pairs of tights, 4 thin long sleeve shirts, 1 thick long sleeve shirt, 1 set of pajamas, 3 bras, and 3 t-shirts. In the medium set to the right, I have 6 pairs of socks, 16 pairs of panties, 1 pajama set, 1 swimsuit, 3 Cami tops, 1 hand towel, 2 washcloth, and 1 swim cap. The cubes were put inside of a duffel bag for my week long trip and it works perfectly. You just have to do some squeezing depending on the size of your duffel. There was no breaking, very durable, and very easy to show TSA at the airport in the event they needed to search my bag.. I would highly recommend these cubes. It definitely cuts down on having to check in a bag due to over-packing or improper packing. This is definitely one of my best purchases!