Integrated vacuum compression system Holds "5 times!" more items than a regular backpack Dimensions: Inches: 19" × 13" × 6-8" (After expansion) Centimeters: 49cm × 32cm × 15-20cm (After expansion) Airlines Carry-On Limit: Inches: 22" × 14" × 9" Centimeters: 56cm × 45cm × 25cm Weight: 3.9 lbs (1.7 kg) Vcapacity: Regular: 25L Extension + Compression: 55L Materials: Main Material: Waterproof Oxford cloth (Waterproof/Wear-Resistant/Moistureproof). GRScertified, PFC free. Other Materials: Nylon herringbone... Package Contents:1 × Vacuum Backpack How to Use? 1. Place the items to be loaded into the various compartments in the backpack. 2. Open the cover of the vacuum pump interface on the backpack. 3. Use our vacuum pump or a vacuum cleaner with corresponding interface to suck the air out of the backpack and activate the vacuum compression system to compress the items to the desired size. 4. Close the cover of the vacuum pump interface on the backpack. Precautions: Equipped with a 28mm vacuum interface, you can use a household vacuum cleaner with the corresponding interface for vacuuming. When using a vacuum compression system, make sure there are no sharp objects inside the backpack that could damage the backpack or the compression system.