Wire-O binding is single sheets of paper printed on both sides, cut down to trim size and collated in page number order. The wire, often referred to as wire-o or twin-loop / double-loop binding, has pre-formed pairs of two small loops of wire that run along a c-shaped spine that looks like a comb. These wire loops are inserted through each of the square holes that have been punched through the edge of the printed book’s cover and pages which allow the pages of your book to line up precisely. A wire closer squeezes the spine until it is round and securing the cover and pages. The binding can be on the left or on the top, depending on how the project is designed.