They are auto-leveling my friend.. its basically a scan to determine if you are hauling weight, and if they need to be pointed more towards the ground etc. Plus its also a system check to ensure they are functioning thru their entire range of motion.. Go over a speed bump real slow.. you will notice they angle down to avoid blinding other drivers. As far as the mechanism that allows the movement? I am going to guess at reflectors more than shutters directing the light, but thats just a guess. Hope this helps