The SCS 105ST2030 Transparent metal-in static shielding bag is designed to provide a static-safe environment for sensitive electronic devices. It is manufactured from a polyester, metal, polyethylene laminate. The polyester dielectric, in concert with the metal layer, is intended to provide shielding against Electrostatic Discharge (ESD) and to help minimize the penetration of electric fields. These Static Zip Bags measure 20"x30".