Hardware stores sell a lot of chains. We’re talking about the ones you put on your doorframes. They break easily. You open the door a crack, and immediately someone can stick their foot in; apply a bit of force and crack, the chain busts and a burglar, thief, your nasty ex, or whomever, is standing right next to you.
But that’s not the main reason why we’re not a big fan of these. Many who buy them think it means their home is secure. It’s not. Things worse than feet can fit through a door opened even if the chain holds. These include a gun and a knife. Want to see who’s on the other side of your door? Install a peephole. If that’s not allowed? Just talk to the person. If you don’t recognize their voice, for sure, don’t open the door. No chain, no pain. That’s our answer and we’re sticking to it.