Strong lock, consisting of a magnet and a counter plate, mounted on the door frame and the door respectively. When the counter plate is pressed against the magnet and the latter is energized, the lock is activated. The magnet is deactivated by cutting the voltage. Choice of version with coil signaling or with coil and door position signaling, timer and LED indication. 12VDC and 24VDC power supply and horizontal or vertical mounting.