3M D271030 Moisture Barrier Dri-Shield 2700 Bags are manufactured from a laminate of multiple layers of aluminized polyester and polyethylene. Polyester provides puncture resistance. Metal layers are intended to provide shielding of Electrostatic Discharge (ESD) and to help minimize the penetration of electric field. The D271030 comes in a pack of 100 bags sized 10 inches by 30 inches.