1PAPER CAPACITY: These double loop binding spines can hold up to 40 sheets of paper (A4, 70g), allowing you to bind multiple documents or reports together. 2METAL WIRE CONSTRUCTION: The binding wire is made of premium metal iron wire, ensuring durability and strength. It enables easy binding of papers and provides long term storage capability. 3NYLON COATING: The outer surface of the binding coils are coated with nylon, giving it a glossy finish. The nylon coating provides resistance to corrosion and wear, ensuring a long lifespan of the binding spirals. 4PERFECT SIZE: Each binding spirals has a diameter of 5/16 inches (7.9mm) and a thickness of 0.8mm. It features a 3:1 pitch with 34 double loops, allowing for 360 degree rotation. 5VERSATILE COMPATIBILITY: These double loop binding coils are compatible with most wire binding systems that use a 3:1 pitch and 34 teeth pattern. They are ideal for binding important documents, files, or reports for upcoming presentations or projects. 100 x Binding Spines