Item Type: Spiral Binding Coil_x000D_ Inner Diameter: Approx. 13mm / 0.51in_x000D_ Type: Stationery accessories binding consumables. 1For Your Paper: Designed to have 13mm inner diameter, the spiral binding coil enables smoother page turning for reading and writing. 2Better Binding: Easy to install and remove, you can also cut the binding comb into your preferred length for your needs of storage. 3Large Capacity: Able to clip a large amount of sheets, the binding spine suits perfectly for office, classroom, library and so on. 4Great Material: Made of premium plastic material with pretty colour, not easy to deform and very durable with corrosion and long use. 520Pcs in Total: There are 20pcs spiral binding coil in the set, and the large quantity will simplify the replacement of damaged ones.20 x_x000D_ _x000D_ Spiral Binding Coil