Biaggi Zipsak Boost! Foldable Underseat Carry-On Expands to Full Size Carry-On. Convenient & Expandable: This collapsible design weighs only 3.85 lbs! It starts as a compact 16"x15"x9" pouch, easily fitting into overhead compartments. Need more space? Expands 5" upwards, to become a full sized TSA-approved carry-on (21"x15"x9"). Organized & Spacious: Main compartment for clothes/shoes plus 3 exterior zippered pockets. Easy Mobility: Four spinner wheels for 360° rolling in multiple directions. Durable, water-resistant nylon fabric ensures longevity.