Wire-O binding wire, also called "duo-wire" or "twin-loop binding wire", is a versatile binding spine that pairs security and durability with style and affordability. 3:1 pitch wire-o binding wires are designed to fit the signature hole pattern of a 3:1 pitch wire binding machine (three holes per inch = 32 holes per letter-sized sheet). Wire-O binding wires from Lamination Depot are fully compatible with all standard wire binding machines, including models from Akiles, USI, GBC, Ibico, NSC, Tamerica, Fellowes, and HIC. These heavy-duty, metal binding spines are available in a wide range of colors and sizes, and are perfect for reports, presentations and any other book binding projects.