Transparent cover highlights your title page. Durable, 8 mil clear plastic protects letter-size bound documents from spills and tears. Comb binding covers are pre-punched for easy binding. They are not for use with thermal-binding systems. Squared corners give your reports a crisp, professional look.Transparent cover highlights your title page. Durable, 8 mil clear plastic protects letter-size bound documents from spills and tears. Comb binding covers are pre-punched for easy binding. They are not for use with thermal-binding systems. Squared corners give your reports a crisp, professional look.