Wire-O Binding, also known as Twin Loop, Double-Loop, Double-O, Duo-Wire, or simply Wire Binding, is a popular binding method for professional publications. It is similar to a coil bind but results in a more sophisticated look. The Wire-O binding method utilizes pre-formed pairs of wire loops that run along a C-shaped unit and are clamped closed until they form a perfect circle, thus securing the cover and pages. Wire O binding produces a very impressive final document that can accommodate pages and inserts of varying thicknesses, including dividers or index tabs.