Fellowes 5:1 pitch 28mm black metal binding spirals (50 units) 5111301 offer maximum reliability for binding up to 250 sheets of A4 paper. Available in packs of 50 units with a diameter of 28 mm and a 5:1 pitch, these black metal spirals ensure that heavy documents remain well-structured. The black tone gives a formal and tidy look to the whole set. Excellent for corporate filing, meeting minutes and compendiums.