Features 13mm inner diameter: stationery accessories, binding accessories, inner diameter for 13mm, suitable for students and teachers. Good gloss and no breakage: possesses a good surface gloss, strong adhesion, wear resistance, rosiness, aging resistance, not easy to break or fade, smooth turning of pages, can be used repeatedly. BINDING METHOD: can be tied manually by punching suitable holes, which can be easily done by any office, student group and individual. Durable with a long service life: thanks to the durable and robust plastic spines, you can easily assemble paper and store them for a longer period of time. Total 10 pieces: the package contains a total of 10 binding spines, enough to replace and use, very practical. Specification: Item Type:Binding Spines Inner diameter: approx. 13 mm / 0.51 inches. Type: Stationery Accessory, Binding Accessories Package list: 10 x spines. Package List 10 x Binding Spines