The MINI ALERT ALARM uses passive infrared technology to protect a room from a wandering toddler going some where dangerous! Both my kids would knock down baby gates with ease. Even the most watchful parent can have it happen. Just put the motion detector in a place where you can not have a child go and when they try the alarm will sound. It may even stop the child from going further if it scares them. It will get someones attention fast. The unit works by Producing an infrared triangle, the Mini Alert creates an unseen barrier that is impossible to penetrate without setting off the alarm! It may just save the day. I would use a gate too and be double safe! Battery operated, the Mini Alert needs no wiring and can be easily moved to a new location. Mounting bracket included. Requires three AA batteries.