Abstract: A flexible resilient ribbon having first and second conductive surfaces is wrapped over the top edge of a pocket wall forming a bowed-out first conductive surface adjacent to the top edge of the wall which biases the first conductive surface into contact with the second conductive surface when a card is absent from the pocket, an alarm circuit IC terminal is connected by a network which includes a fixed resistor to power supply negative and the first and second conductive surfaces each of carbon, in series removable contact, connected to power supply positive.