comb binding
US /koʊm ˈbaɪn.dɪŋ/
UK /koʊm ˈbaɪn.dɪŋ/

1.
a method of binding documents using a plastic comb that is inserted into rectangular holes punched along one edge of the pages
:
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The report was finished with a professional comb binding.
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We need to buy more plastic combs for the comb binding machine.