1、20 Sheets Capacity: This double coil binding spine can hold up to 20 sheets of 70g A4 paper, which is very practical and can be used for a variety of situations. 2、Iron Inner Wire: This double coil binding spine is made of iron wire, which is sturdy, wear resistant and not easy to damage, and can be use for a long time. 3、Nylon Coating: This double coil binding spine is nylon coated for a glossy surface, erosion and abrasion resistance, and a long service life. 4、6. 4mm Diameter: This double coil binding spine has a diameter of 6.4mm and a thickness of 0.8mm, each spine has a 3:1 pitch and 34 double rings that rotate 360 degrees. 5、Wide Application: This double coil binding spine has a wide range of applications, and can be used for documents, books, notes, reports and more. 100 x Double Loop Wire Binding Spine Item Type: Double Loop Wire Binding SpineMaterial: Iron, NylonBinding Diameter: 6.4mm (1/4 in)Binding Capacity: 20 Sheets (A4, 70g)Teeth Number: 34 TeethRatio: 3:1