Ultra-durable Poly View Colored File Folders are constructed of waterproof, tear-resistant polypropylene; and though they're open on three sides like any standard file folder, they also feature a built-in tuck-flap to lock documents securely inside. Available in a range of vivid, translucent colors, they're ideal for color-coding while allowing you to read the top and back sheets within a file, making it possible to develop and insert a contents index and/or a comments sheet when desired. Equally durable poly tabs stand up to frequent referencing, and the tabs' included self-adhesive labels accept pen, pencil and marker ink. Folders are manufactured acid-free to accommodate archival document storage.