They are archival safe and are made of a clear/transparent 4 mil plastic. Securely store your clear stamps, wafer thin dies, stencils, embossing folders and more! The pockets are a great way to store your Avery Elle clear photopolymer stamp sets and custom steel dies. Each pocket will fit one standard 6x8" clear stamp set. Store the pockets in a storage basket/bin or clip them up if you wish. Slide the stamp set/card stock sheet into the pocket.