The bar is adjustable and can be used two different ways

With the bar being adjustable this allows you to place it in the groove of a sliding glass door or you can raise it higher to go from the wall to the middle of the sliding glass door.

Still, the bar might deter someone in certain situations

The other way to use the Sabre bar is to easily remove the black end that would prop against the door knob if used the way just described and lay the bar on the sliding door track to prevent the sliding door from being opened

There is NO siren included with the item as advertised, but the actual bar is fantastic.

I like that the bar is adjustable so I can shorten it and leave my door open a little more for air flow while still preventing someone from sliding the door open (unless they decide to break the door)

I have not ever seen a workable bar like this.

As noted on the packaging materials, this bar works best on doors that lock, as the bar is not seated as securely on a unlocked door as you can push the door open partially even with the bar set tightly and dislodge the bar.

this fits perfect as if there were a knob.