These vacuum-sealer pouches from VacMaster measure 8-inches by 12-inches and are 3 millimeters thick (model 30723. Bag material is transparent nylon/polyethylene, transparent gloss. Package of 1000. For chamber vacuum sealers these pouches work superbly but they simply do not work in non-chamber style sealers. Microwaveable; can also be boiled or cooked sous vide. Designed to facilitate a tight seal in VacMaster and other brands of vacuum sealer. Bags are F.D.A. approved and are B.P.A.-free. As has been scientifically verified, vacuum-sealing is the best means available for preventing food spoilage & freezer burn. It keeps food edible for extended periods of time, up to five times longer than other means of storage.