Fellowes 5:1 pitch 26mm black metal binding spirals (50 units) 5111101 were developed for thick publications and intensive use. This box of 50 units contains 26mm diameter black metal spirals with a 5:1 pitch, designed to bind up to 230 A4 sheets. The high resistance of the metal prevents the document from sagging over time. Ideal for extensive school textbooks, audit files and theses.