Spiral binding consists of a continuous wire, which is coiled through evenly spaced holes that have been punched into the pages of a book. The spiral wire can be made of metal, plastic, or plastic coated metal. Plastic is available in a variety of colors, but the metal spiral has a limited color selection. When the books are open, the pages lie flat. The pages can also be folded over completely, which makes spiral binding a good choice for training manuals, cookbooks, notebooks, and calendars.