On May 18, 1990, the United States Postal Service began a six-month marketing test to sell stamps through Automated Teller Machines (ATMs). For this test, the USPS developed a stamp that was radically different from any it had previously issued. To meet the strict engineering requirements of ATMs, the stamps were made of a specially formulated polyester film. The panes of 12, which were the same size and shape as a dollar bill, were dispensed from the ATMs just like cash. In addition to offering customers the convenience of round-the-clock access to stamps, the ATM issues also offered the ease of peel-and-stick application with no licking or tearing.