The Zipsak Boost Max starts off as an easy to store pouch, transforms into a smooth rolling 4-wheeled carry-on, then expands 11 inches upwards, converting it into a large check-in bag! Our custom sized Zipcubes add structure to the bag and enhance performance while providing even weight distribution. When not in use, the Zipsak folds neatly for storage under a bed, on a shelf, or in a drawer. The Zipsak is made from extremely durable, tear-proof, and water resistant nylon fabric. Dims Not Expanded: 17"x18.5"x9.5" Dims Expanded: 28"x18.5"x9.5" Dims When Folded: 18.5"x9.5"x4.5" Weight: 4.9 lbs Packing Capacity: Interior Dims: 15"x18.5"x9.5", expanded 26"x18.5"9.5 Litres: Not expanded=43, expanded=75