The count is not arbitrary — a twelve tab set is bought for a monthly scheme, and choosing a count that maps to nothing means guessing where something went. Reinforced or mylar edges are what stop the punch holes tearing on a file opened daily. Check the tab extends beyond your page size. See binder dividers, 20 tab dividers and binders.

12 tab binder dividers arranged inside an open office binder with monthly project sections, folders and stationery.
12 Tab Binder Dividers

Shop 12 tab binder dividers for monthly records, binders, reports, school folders and office filing.

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