The coil binding method is gaining popularity. It offers a flexible coil that withstands tough handling. The coil is offered in a wide variety of colours. Books lie flat and open cover to cover 360°. Coil-bound documents may be bound up to 5cm or 2” in thickness. Coil binding is excellent for odd sized reports. Coil is available in 4:1 (4 holes per inch) or 5:1 (5 holes per inch). The 4:1 and 5:1 coils are not interchangeable.