Twin-loop wire binding, also known as Wire-O binding or double-loop binding, is a bookbinding method that involves threading a double-looped wire through a series of closely spaced square holes punched along the edge of a stack of pages. The wire is then crimped at both ends to
keep the pages securely bound together. Wire-O binding is a popular and professional binding method for a wide range of documents, such as reports, proposals, calendars and journals. It allows the pages to lie flat when opened and provides a sleek, modern appearance.