Abstract: A security device for use in retail stores for the prevention of retail theft, which includes an alarm mechanism which generates an alarm signal in response to electrical power being applied through a switch mechanism. The switch mechanism is controlled by a signal provided by a closed circuit mechanism. Whenever a closed circuit condition is created, for example, by cutting the cable which mechanically connects the retail item to the security device, electrical power is applied to the alarm mechanism. Thus, if a battery is used to supply electrical power, such battery is only drained during closed circuit conditions, maximizing battery life.

Abstract: A product monitoring device including a releasable locking device adapted to be secured to a product and actuatable between locked and unlocked positions. The locking device consists of a pair of movable members, one of which mounts a bimetallic member consisting of bimetal elements having different temperature coefficients of expansion, the bimetal elements being separated by an insulator. The locking device includes a detent cooperatively associated with the bimetallic member to maintain the members in a locked position. The device uses an electrifiable key for heating the bimetallic elements to effect displacement thereof relative to the detent to facilitate movement of the members to an unlocked position. The device incorporates structural features which increase strength in operation, and further serve to make unauthorized opening and/or breakage of portions, with the intent of permitting separation from an article to which attached, more difficult.