Abstract: A portable plastic card is assigned to carry relevant inventory and other data for each of a given number of items. The card both stores and displays sufficient data to make it useful as an inventory control tool. The visual data is a persistent electrochromic display that shows select portions of the data stored in the magnetic track. Two edges of the card are tapered to prevent their improper introduction to a card reader. A diagrammatic drawing shows the preferred use of the card in a slip-issuing mode.