To vacuum seal with the FoodSaver® system, you must use FoodSaver® Bags and Rolls. They are specially designed to be strong enough for vacuum sealing and the waffle pattern in the bag is a patented design that makes sure air does not get caught in pockets around the food.
FoodSaver® Bags and Rolls have five layers, including an outer layer of nylon. This configuration completely prevents air and moisture from getting back into the bag and prevents odors from getting out or in. Other plastic bags allow air to seep through.
If you want to use your FoodSaver® appliance to re-seal, but not vacuum package a bag (without removing the air first) you can use it on Mylar type (strong, thin polyester) or stiff plastic bags, not any other types. For example, you can re-seal potato chip bags.