The picture of the mk1 with the arm was just to show you where it is to be placed on the arm. Sorry if that confused you, I was just being lazy and didn't feel like making another quicky arm for the mk3. but anyways for you I did another arm. The entire thing will consist of the main body, the 2 holo-screens, and the straps. As for using it, the interior of it is lined with a skin sensitive material that allows the trooper to interact with it mentally. It also has the holo-emiters that display the battle field in 3D and detect enemy movement.