A chain latch is a small thing, but it creates a useful pause. When the bell rings, instead of opening the door fully, you can open it just a crack with the chain on. You see who’s there, talk, and decide whether you’re comfortable opening fully.
It’s especially helpful for people who live alone, elders, or families with kids who might rush to the door. Even if someone pushes from outside, the chain gives a barrier that buys you a few extra seconds to react.
It won’t stop a determined intruder forever, but it changes an instant full opening into a controlled, partial one. Sometimes that small gap is all you need to say “No, thanks” and safely close the door.
