Moisture barrier bags, also known as foil bags, metallized bags, which are manufactured from a laminate of multiple layers of aluminized polyester and polyethylene, and sometimes provide moisture, corrosion and shielding protection for sensitive components.

They are heat sealable and suitable for vacuum packaging. Most contain Polyester (PET) for puncture resistance. The metallic layers provide shielding from Electrostatic Discharge (ESD). Barrier bags are mainly used to package ESD sensitive devices before they get placed on a circuit board.