This sealer does not use a piston pump like most other sealers use. It removes the air with a fan. There is air left in the bag, it doesn't create a vacuum. The bags are not ribbed and you have to fit them over a hose under the lid. The bags are folded on a roll and you have to seal three sides to create a bag. I was also dissappointed in the weight of the bags. They are thinner than Ziploc bags. You cannot use canisters with this one.