Abstract: The improved guard plate of this invention is used to protect the cylinder of a lock. It includes a relatively flat body, attached to the door in the vicinity of the cylinder, and a disc rotatably mounted between the door and the flat body. In an open position, an opening in the disc permits access to the cylinder; and, in the closed position, the solid portions of the disc do not permit access to the cylinder. In adition, rotatable fingers are provided so as to lock the rotatable discs in either the open or closed position. Further, a stud extends from each of the rotatable fingers into and through the door. On the end of each stud is an electrical contact which may come into intermittent contact with an electrical contact positioned on the inside surface of the door. Thus, rotation of the rotatable fingers in the incorrect direction or too far in the correct direction will cause touching of the two electrical contacts and completion of an electrical circuit which will activate an alarm.

Abstract: The improved guard plate of this invention is used to protect the cylinder of a lock. It includes a relatively flat body, attached to the door in the vicinity of the cylinder, and a disc rotatably mounted between the door and the flat body. In an open position, an opening in the disc permits access to the cylinder; and, in the closed position, the solid portions of the disc do not permit access to the cylinder. In addition, rotatable fingers are provided so as to lock the rotatable discs in either the open or closed position.