A. Twist-up compression design, no vacuum needed, just use your hands to grip, twist and zip. More convenient when traveling and don't need to worry about shirts getting wrinkled. Vacuum bags are extremely lightweight. 12 pieces vacuum bag, including 4 different sizes, weighs only 430 grams, suitable for travel or home seasonal storage. B. The bags protect clothes from dust, mold, odors and moths. The reasonable magic design allows the air flow to work in only one direction, which maintains the vacuum for a long time. It fits well between the film and the sealing zipper, making it easier to seal. Tip: Push the zipper back and forth 2 - 3 times to make it tighter. C. For storing pillows, coats, cotton clothes, jeans and other heavy clothes: Medium size (40 * 50 cm * 3 pcs. and 40 * 60 cm * 3 pcs.). For light clothes, including sweaters, shirts, short sleeves, etc.: Small size (35*50cm*3pcs). D. Travel Vacuum Bag Set with 4 Sizes Bags. Material: PA + PE Material E. How to use the vacuum bag: 1. Open the double seal roll vacuum bag. 2. Put the folded clothes into the vacuum bags. 3. Pull the slider back and forth several times to confirm that it is sealed. 4. Start with the seal and squeeze it with your hand. Slide the zipper back and forth 2 - 3 times to make it tighter. F. Package Contents: Vacuum Bag Travel Storage Bag (3 x 35*50cm, 3 x 40*50cm, 3 x 40*60cm, 3 x 50*70cm)