Iron gym ?

Ok soo I been hearing about iron gym .

And I wanna know what muscles do you build

By using it and

What exercises you can do with it .

I don't own the product but from what I can see its a pull up bar. I know a lot about pull ups. They're a great exercise. At first they are difficult but you improve very quickly. With a pull up bar you can work your biceps, lats, almost every muscle in your back, traps, and I think your shoulders a little.
According to the iron gym website you can also use it to do some triceps dips. Because you would be doing dips with the iron gym off the ground they won't be real dips, like the kind you can do using a dip rack. Nevertheless, you can get a tricep workout in too. Its nothing you can't do without a chair.

As for using it to do sit ups, that's crap. Situps are much more effective when you keep your toes on the ground and have nothing to pull yourself up with.

If you are willing to do the work, you can get your upper body pretty jacked using this thing. All it is a pull up bar that attaches to doors easily. You can use it to get a ripped back, traps, big (not huge) biceps, and your triceps can get a little workout.

Woukd it work the chest