These Wire-O binding wires, also known as "double loop wires" or "double loop binding wires", are a versatile binding spine, with a 2:1 pitch and 21 rings are available in a wide range of sizes that offer security and durability while keeping all the pages together. The metal binding spines measure around 278 mm in length and are designed for use with letter paper. However, they can also be easily cut with cutting pliers to accommodate books with spines less than 297 mm and used with the RAYSON TD-1222 binding machine, perfect for binding. reports, presentations. Wire-bound documents lie flat for photocopying, reading and note-taking, easy to use. Use with a binding machine to create your own professional reports. Color: sliver, pack of 100, size: 3/8 inch, binds up to 50 sheets of Letter size paper.