It's a device that sits on top of your monitor and picks up the movement from a special ring or wand or most often used a small reflective dot placed on your glasses, forehead, mic boom or headban on your headphones. By moving your head the view can be manipulated in your sim. Although it may seem odd and beg the question "how will I see the monitor with my head turned" the way it works is it splits your monitor into area's or regions. You assign a certain ammount of movement to each region so say for example you split your monitor into 4 sections vertically 'ABCD' (could be more or less areas.
A B C D
Moving your head to the B or C position perhaps gives you 45 degree front left and right or perhaps left and right view whilst moving your head to A or D gives you 45 degree rear left and right or a six view. Movement can be as small or large as you want.
It can be made to work in the game without support but does not work as well as if the game has a special .dll written for it. The manufacturers say this .dll is easy to write and only a small file. Games like FS2K2 use it very well, it can be used in IL-2 and Forgotten Battles will have direct support as will Warbirds III soon apparently. For more information visit their
web-site