Packing cubes achieve compression primarily through a dual-zipper system rather than vacuum technology. First, you fill the cube with your clothing using the main zipper, similar to a standard packing cube. Once closed, a second "compression" zipper runs around the perimeter of the bag. As you pull this second zipper shut, it physically squeezes the air out from between the layers of fabric and draws the top and bottom panels closer together. This mechanical force significantly reduces the bulk of your items, typically decreasing the volume by 30% to 50%. While this doesn't reduce the weight of your luggage, it allows you to fit more items into a smaller footprint, which is ideal for carry-on travelers in 2026. High-quality compression cubes are made from durable, tear-resistant materials like ripstop nylon to withstand the high tension placed on the seams during the compression process. For maximum efficiency, many travelers "roll" their clothes before placing them in the cube to further eliminate air pockets before the final zip.