In this set of 4 bags the one that slips in the narrow gap under the shelf for the retractable hood is essential for proper use of the boot space. It can hold enough clothes for a week (for a man) or 12 bottles of wine, but takes up no space in the main body of the boot space. You can also slip a computer bag on top of it if needed. It might be nice if this could be ordered on its own. The two larger bags which fit in the main space of the boot make good use of the space and leave room for a food hamper or handbag on the side. The least practical is the long thin bag that fits under the floor of the boot. Mine did not fit properly in the space, and this space is probably better used for tools or lose items.