Ring of Invisibility question.

[Qayinisorouse]

If i own a ring of invisibility - does that:
1. Equal Improved invisibility - if i attack i am not invisible anymore?
2. Normal Invisibility - after i attack i'm seen again.

If its the 1st, very simple, however if it's the 2nd, when do i return to being invisible? on my next turn - automatically?
the text says "By activating..." so, is this a free action? what's stopping me from attacking\casting a spell and then "Activating" it?

Thank you!

[Grey_Mage]

Option 2.

You appear immediately upon an attack or upon completion of the duration (3 mins if memory serves).

Standard action to activate.

[Claxon]

Ring of Invisibility is a standard action to activate, and essentially the ring cast Invisibility (as the spell) on you with a caster level of 3. That would mean the invisibility lasts 3 minutes (and then has to be reactivated) or would end when you do something that ends regular invisibility.