The Slider Bags do not seal as well as the press to close ones .....and they leak too....Hate the pleat at the bottom of the Bag... Hate that they do not have a full open top because they take away about 1 inch or so for the slider thing.....making it hard to get things in the bag......grrrrrrrrrrr....they sux and I will never buy them again...butttttt ...ziploc is safe because the original ones that press close are great...