Lifeline Jungle Gym

Any ideas what this would connect to?

I have one of those over-the-door Iron Gym things that might work…

According to someone on Amazon:

*There’s an end that you close in the top of the door that you hook onto. Make sure the door opens away from you though, so there is no chance of the door opening on you while using it. I used the eye bolt that I have my heavy bag attached to for me. *