50mm Spiral Binding Coils

As long as your punch is a standard 4:1 pitch machine, it will punch the correct hole pattern for a 50mm coil — pitch is what determines compatibility, not diameter. What can differ at this size is the insertion process: threading a 50mm coil by hand through several hundred punched holes is slow and physically awkward. If you're binding documents at this size regularly, an electric option from coil binding machines rated for large-diameter coil makes a meaningful difference in production time.

Standard coil length for letter-size documents is 12 inches, which accounts for the 11-inch binding edge plus a little extra material needed for crimping both ends after threading. If your manual uses legal-size sheets instead, you'll need 14-inch coil to fully cover that longer binding edge — a 12-inch coil simply won't reach the full length of a legal-size document. Confirm your document's exact trim size before ordering, since using the wrong length coil leaves part of the binding edge uncovered and unprotected.

Yes — a coil that's noticeably larger than the actual page stack will look loose and can allow the pages to shift or feel unstable within the binding, even though it will still technically hold. Measure your assembled, punched stack before committing to 50mm; if it's significantly thinner than expected, MyBinding's coil binding supplies covers the full diameter range so you can size down to a tighter, more finished fit.

Color is a cosmetic choice only — it doesn't affect the coil's rated capacity or durability, since all colors in a given diameter and pitch are made from the same food-grade PVC material. Once a coil this thick is threaded, coil crimpers are essential for securing both ends properly. Choose color based on how you want the document to look or whether you're coding by department.