These 8" x 12", 100-count vacuum sealer bags (model 30-0101-K) are compatible with vacuum sealers in Weston Pro Series line (and work well with a number of other brand vacuum sealers as well. It is well established that the proper vacuum-sealing of meats and vegetables virtually eliminates freezer burn and increases the shelf life of foodstuffs, facilitating long term food storage. These bags are an excellent choice for those needing vacuum sealer bags in quart size foods stored in these bags can be reheated, even to the boiling point, while still in the bag, and can also be put directly into a microwave (provided one pierces the bag before engaging the microwave. Bags are 3.0 millimeters thick and two-ply. Note: this item is identical to Weston's product 30-0101-W except product 30-0101-W is delivered in a box while this item listed (30-0101-K) comes in a plastic bag. In the unlikely event that you are giving vacuum sealer bags as a gift (you romantic fool, you) then 30-0101-W is the better choice in that it is packed in a nice box however, for that reason product 30-0101-W costs a bit more than 30-0101-K.