Collapsible backpacks are a handy means of storing useful luggage in a small space. Because they can be rolled up into a compact shape, these packs can be kept in automotive storage compartments, tucked into suitcases when flying to a vacation spot or even inside another backpack as a backup if needed. Up until now, the collapsible packs I've worked with have been useful but simple. They've mostly been day packs that offered little in the way of added features or extra capacity.
