Spiral-O wires look similar to twin loop wires, but they are specially designed to fit the same 19-hole punch pattern as comb binding. Spiral-O wires have 19 loops (similar to binding combs).

Like duo-wire, Spiral-O wire offers tamper-proof binding that is durable and lays flat when opened. The biggest advantage of binding with Spiral-O wire is that it uses the same pattern as comb binding, which means that users who already own comb binding punches do not need to purchase an additional punch, however it does require the use of a wire closer to secure the bind.

Spiral-O wire is available in sizes ranging from 1/4" (20-30 sheets of standard 20 lb bond paper) to 1" (190-220 sheets of 20 lb bond paper), and in seven standard colors. The per-wire cost for Spiral-O is significantly higher than that of twin loop wire, so if you plan on binding frequently, you may want to consider twin loop binding instead.