door chain
security chain
security door chain
chain door-fastener

The door started to open but caught on a security chain.

I opened the door a bit, leaving the security chain in place.

However, the door is stopped by a security chain and cannot be opened.

When the door finally opened, it was on a security chain.

With the security chain in place, the door opened only about three inches.

A young woman peered out at me from behind a security chain.

I cracked the door and looked at him over the security chain.

Now I could hear the security chain being slid to the side.

I only knew one man who could release a security chain from the outside.

The door started to open, only to be stopped by a security chain.