Date stamps, also referred to as daters, are available in several sizes and styles. Changeable date stamps provide an easy way to mark your documents, including: Incoming and outgoing mail, sales receipts and invoices, bills and other important documents, for teachers to mark homework and reports, on food items like egg cartons that require a sell by or use by date. Add personalized custom text to your date stamp to increase versatility. Whether it's traditional or self-inking there's a changeable date stamp for you.