This foil moisture barrier bag is designed to provide protection for ESD sensitive and moisture sensitive electronics, typically SMT (Surface Mount Technology) items. Best practice is to use with Desiccant and a Humidity Indicator Card. The bags are heat sealable and suitable for vacuum packaging. Bags are printed with ESD protective and moisture sensitive warning symbols, and a lot code for traceability. NOTE: Many additional custom sizes are available. Please contact us for more information if your desired size is not listed. - SCS Moisture Barrier Bags Dri-Shield 3400 are manufactured from a laminate of polyester, foil, and polyethylene. The metal layer is intended to provide discharge shielding and to minimize the penetration of electric fields and electrostatic discharges. NOTE: Many additional custom sizes are available. Please contact us for more information if your desired size is not listed.