Flat File is a popular filing tool with fastener for 2-hole punched papers, and the cover is usually made of paper. The metallic fastener originally equipped when launched in 1975, was replaced by plastic fastener after a decade to improve usability and stability. Later, PLUS developed a unique way to bind cover margins with adhesive glue instead of metal staples. This “non-stitch” approach improves flat appearance of the back cover and making disposal easier. With these small but effective improvements, PLUS's Flat File has been standard, user-friendly file excellent for long-term usage.