Mr. Pen- Binder Rings Organize your materials with these binder rings. They come in a variety of sizes so you can choose the perfect one for your needs. The loose leaf binder rings are made of strong and durable iron so they will last a long time. They are easy to use just squeeze to open and pull to close. With these binder rings you can keep your loose-leaf book paper cards key rings scrapbooking projects and other items organized.