Our 16" x 18" 4 Mil Foil bags are heat sealable, moisture protective multi-layer laminated material for effective moisture barrier packaging. All 16 x 18 4 mil Foil Bags are made from PET, AL, PE, Static Dissipative Coating and can be recycled. Our flat open top 16" x 18" .004 Foil Bags has specially selected polymers that reduce ionics, NVR and outgassing. These 4 Foil 16 inch by 18 inch bags are able to be sealed effectively with a vacuum sealer and should use desiccants for added moisture protection.