Not sure what they are… I did a search, and gotten this the picture below.
At my gym, there is a machine where the weights are free, but there are clips, so when you get tired you can clip them to the machine as opposed to having them fall on you.
I am not sure what they are called though; I hope you got what I am taking about.
Btw: do the bar have to be above your neck like the picture shows, its always center/bottom of my chest when I do them.
The exercise I do is very similar to the picture below: