HOW TO MAKE THE COMPRESSION HAPPEN? - There Is a Extra Zipper Outside Of Our Compression Packing Cubes Which Can Be Zipped Up To Flatten The Cubes And Save The Space As Far As Possible. It Just Works Like a Vacuum Sealer. You Just Need To :1) Fold Your Clothes And Flatten Them 2)Pack Clothes In The Cubes And Zip The Normal Zipper. 3)Put A Finger On The Back Of The Zipper In The Space When Compressing The Packing Cubes In Case The Zipper Get Stuck In Fabric. Ultralight&Durable 40D Nylon-"D" is a unit of measurement used to describe the thickness of individual fibers or filaments in a fabric. BAGAIL 40D uses the ultralight fabric has nylon 66. Nylon 66 is high strength and durable, it is ideal for use in products that require toughness. Means BAGAIL 40D is the lightest and most durable fabric. High Quality Zippers- All the zippers we use are SBS zippers, which is smooth and durable, it makes sure the packing organizers could be opened and closed easily. CONVENIENT&MULTI-FUNCTIONAL: Classifying And Organizing Your Belongings For Your Travel Will Become Easy With These Lightweight Packing Organizers.You Can Choose Different Size And Color Set For Different Use Purposes,Such As Short Term Trip Or Long Term Travel.Portable Handle Is Easy For You to Carry The Packing Cube Around And Double Zippers Makes It Easy to Open And Close The Packing Organizers. 6 SETS INCLUDE: 1L-15*12.75*3.5 inch; 2M-14*10*3.5 inch; 1S-11*7*3.5 inch; 1 Slim-14*4.5*3.5 inch; 1 Shoe bag-17*10*4.3 inch.