It's up to you how you use them! I'm selling these to declutter. They are all compression sacks. I used them to compress clothes and sleeping bags. Some of the Sea to Summit sacks have stains. Please understand that these are from a layman's perspective, and I'm selling them with no claims and no returns. Sea to Summit eVent XS 6 liters X 10 liters Sea to Summit Cordura M 14 liters Granite Gear Yellow XS 10 liters Granite Gear Green M 18 liters They become oval-shaped, so they're good for putting in the lower section of your backpack, such as for sleeping bags (I was compressing a NANGA DX900 1.5kg sleeping bag).