HERE'S HOW IT WORKS:

The BackSeat Minder senses when your car’s rear door is open for three seconds or more. Once you start your car, the system is activated. As soon as the ignition is shut, a distinct chime will sound. The chime can only be turned off by pressing a button located on the inside of the car’s rear doors. The BackSeat Minder system was designed to anticipate real life situations. It’s just about impossible to seat a child in a car in less than three seconds – but you can toss in your coat or bag in that time. Such activity will not activate the system. Similarly, if the car is not started within several minutes after the rear door was opened, the chime will not sound. The Back-Seat Minder even has a temporary manual override button. By pressing the button five consecutive times the system is paused for three hours.

PROFESSIONAL INSTALLATION REQUIRED.