It's butterfly hinged type movement. It's in the beginning of this Phil Heath clip
the powerhouse gym on the campus of Michigan State has one. Pretty interesting, it felt different than the standard bench machine, it did hit my chest at a different angles, felt like heavy flies. LOL, it is bad for the ego, you really can't load up on it. As a change of pace from your your usual chest work out it is great.
fyi, that powerhouse gym has moved even further off campus