Degol:What Is a Door Chain?
A chain or door restrictor is a simple device that allows you to control communication with people standing on the outside of the door. These tools are typically just a couple of inches long, attached to your door and doorframe around head height. The chain prevents the door from opening beyond a crack. There’s just enough space to communicate with the person on the other side and to receive small packages.
Door chains and restrictors offer a low-tech layer of added safety and security for dealing with strangers on your doorstep. There are two main points to consider before choosing a door chain:
Make sure it’s of the highest quality
It has to be installed correctly