This envelope file folder is made of wool felt. It is strong enough to catch A4 paper, such big capacity improve work efficiency; Envelope shape design with snap fastener closure, stylish and easy to take things out. It's perfect for office, school, business data bill receipt, test field, put in all kind of, carrying plenty of important documents, working, conference, school, test field, etc. Custom logo is available. Email us!More information, please send your detailed requested for quotation.