 Once the flip lock is installed, and it's very easy to install, once they flip it, they're safe in their rooms until they can call 911 and get some help from the police. Right, because whenever you see the lock on your door, sometimes you're not sure if you locked it or you didn't lock it. This way you know for sure your door is secure. By just looking at your lock, you'll know when it's locked, and you'll know your flip lock is holding that door up.