they work as long as the seal is tight after the air is sucked out. I've had some where there was no problem and a few that expanded before I wanted them to.

Be prepared for lots of wrinkles. In everything you store.

ML

I love them! Just purchased some more recently and realized I hadn't been using them correctly (took the time to actually read the directions!). The air is squeezed out through the bottom of the bag rather than the top which was counterintuitive to me.

I've actually been surprised at how few wrinkles I've had. One top I packed for last trip came out wrinkle free and I had totally expected it to be a wrinkled mess. Maybe fabric content has to do with different experiences? At any rate, they get a thumbs up from me:)

I bought a box of space bags at Costco a few years ago. They were great while they worked, but none of them lasted. Eventually they all started leaking air.

I use them for certain things and like them (most of mine are the large ones with the vacuum attachment for suction). The tiniest pin hole can render them useless, however. I like them for storing seasonal bedding; I have a bunch of pillow forms that I only use during the holidays and I can get 6 pillows into one bag and reduce it to something manageable . I also have the hanging ones that I use to store hubby's sport coats that he only wears once in a while. I haven't experienced wrinkle issues with the things I've stored.