Door Security Bar

No way to know, from here. About the time the make a better lock, a better burglar comes along. I figure do what you can, and make 'em work for their booty.

It is stronger than any other lock per dollar cost.

It is a function of the material of the bar and the strength of what the bar is resting against.

For example, let's assume one would have a bar made from several drinking straws taped together resting against the base of a concrete wall. We could conclude that the wall would be a nearly impossible thing for an intruder to move. We could also conclude that the drinking straws would be extremely easy to overcome.

On the other hand, let's say the bar is constructed of 3" diameter steel what the bar rests on an occasional chair. We could conclude that the bar is probably stronger than anything else in that area and won't fail. However, a small child would have little or no problem moving the chair.

Simply placing the bar on a tile floor would be a poor choice because only a minor impact could knock it loose. You would need a wall, or similar, to wedge the bar against to prevent it from moving.

What is it the rest of the time?

Jon

The rest of the time it's...

.. .. .. .. \ / V

...a 3" diameter steel bar.

The "special key" is called a "bump key" and the technique is called Lock Bumping.

Lots of youtube's on how to make a bump key. Here's just one example:

Did you hear about the boy who walked down the street, and turned into a store?