Quick question

I'm going to start buying a couple of absorber panels each week to treat my whole 8x12x8' room. I'm only going to be recording acoustic so what I want to do is deaden the room so i can far-mic without nasty reflections and crappy sounds.

Should I get 2" or 4" panels? Will 2" do good enough of a job?

I'm buying them from here:
http://www.atsacoustics.com/

I'm going to be putting these on the walls.

[Innovations]

The difference they are charging is fairly little so I would go with 4. You really want to equally absorb the full audible spectrum since whatever isn't deadened will seem exaggerated.