Transparent A7 envelopes are made of thick acid free Polypropylene material, waterproof, tear resistant and keeping clean, features clear, you can get the files you need at a glance. Features Wear-resistant Material: thick acid free Polypropylene material Type: Top-opening envelopes, hook and loop closure Dimension: approx. 5.5x7.5inch Application: great for small things organizer and storage, such as stamps, money cash for budgeting, photos etc. Quantity: 20 packs