These are a considerable amount of plastic that you make the bags yourself. The sealer works fine if you are able to get the vacuum sealer to close. But, the heat seal works fine. I have not had to use the sealer because some pre-made bags came with the Vacuum Sealer. But, you still have to get the sealer to close by punching down both corners with your fists. Still, it's nice to have extras just in case you cannot get the vacuum to close and seal.