1. High quality: The library book card is made of 180g cardboard, printed on both sides, easy to write, and not easily torn. 2. Each sheet measures 3x5 inches, making it the ideal size for any private collection or book borrowing system in public, private, or school libraries. 3. A set of 4 different colors, with 25 sheets for each color, totaling 100 sheets, is sufficient to meet your usage needs. 4. These library cards can be filled with "author", "title", "deadline", and "borrower name" 5. Very suitable for office cataloging and detailed library book borrowing. Use these advanced library cards to upgrade, supplement, or add to your book accessory portfolio.