Reliable opening detection . The reed switch with a resource of 2,000,000 openings . Protected against reed switch chattering . Equipped with two magnets_ small and big Additional features . Additional NC input for connecting a third-party detector . Chime feature_ Ajax sirens make a special sound when the door is opening Jeweller communication technology . Up to 1,200 m of radio communication in an open space . Encryption and device authentication to prevent spoofing . Regular polling to display current device statuses Flawless autonomy . Up to 7 years of operation . Pre-installed battery