1180 Sheets Capacity: These wire binding rings are suitable for A4 paper size, with 19mm(3/4in) binding diameter, and it can hold up to 180 sheets of paper. 2Metal Inner Wire: The interior of these double loop binding wires are made of sturdy and durable metal wire, which is strong and durable, allowing you to easily organize papers and store for a long time. 3Nylon Coating: These A4 paper wire binding spines adopt external nylon coating, with glossy surfaces, resistant to wear and scratch, long service life. 4Perfect Size: Each double loop wire spine is 3/4 inch in diameter and 0.8 mm thick. Each spine has a 3:1 pitch and 34 double rings, 360 degree rotation is supported. 5Binding Wire: Use these double loop thread binding coils to bind important documents, files, or reports for upcoming presentations or projects. Compatible with most wire bundling systems (3:1 pitch and 34 hole mode). 50 xDoubleLoopWireBindingSpines