CoverCraft Wolf Roof Top Cargo Carrier - Car Top Bag RCC100BK

Covercraft Wolf Car Top Bag Travel Storage Waterproof Roof Top Cargo Carrier - Black

Moisture Resistant heavy duty tarpaulin construction with weather tight seams
Secures to caravans with roof racks
270 degree sipper access with hook/loop rain flap
Includes storage bag
37.5" x 37.5" x 18"

What a great way to add some storage for a trip.  Give yourself back room in the vehicle for what you need during the drive and to spread out more.