3:1 pitch wire-o binding supplies feature 3 loops per inch and pair with any 3:1 pitch wire binding machine. Also called twin loop or double-o wires, these binding spines offer a classic and clean metal finish that loops great and offers full 360° page turning. 3:1 pitch Wire-O comes in sizes from 1/4 inch up to 9/16 inch, which means it can be used for books from 2 to 120 sheets in size. All sizes are available in bulk, 100 wires per box.
Wire-O binding is known by many names: double-loop, double-o, duo-wire, and also twin-loop binding. This method uses a continuous hinge of double wire loops to hold book covers and pages together. This traditional method of wire binding secures pages, so that they cannot be modified without unbinding the book.