Hanging Features Presstex data board covers and storage hooks to secure up to 6" unburst sheets. Self-loading design and bottom-loading. Acrylic layer on cardboard provides a waterproof cover. Retractable filing hooks are Designed for both single-point filing and drop filing systems, these flexible nylon posts fit up to 6" of attached sheets continuously. Data Center Cardboard accommodates the following posts: 8" and 7."