The suction from pump isn’t that great, I would just use a vacuum or a inflate/deflate pump. The zippers aren’t too accurate in sealing. The closure thread acts just like a ziploc bag so I just pinched the length of the bag by hand- which worked. There’s a type of gasket when you unscrew the plastic cover over the hole, they advise not to remove it so you don’t effect the seal. I had two bags where the gasket fell out on its own. I tried to put it back into place and the seal stayed in place…

This bags work very very well, however if you don't make sure you create sufficient vacuum they will lose the seal in the valve and leak, leading to the bag puffing back up.

I didn’t need all the bags that I got, so it was okay when two of them didn’t stay suctioned. But still, they did. You get what you pay for - mine are just for storing seasonal clothes, so I wasn’t too concerned about it.

I purchased two different vacuum seal bags. These were by far the best. Thick, durable, and do not lose suction. May not work well with oddly sized items.