The Scorpion Aero Skirt is an optional device designed to help quiet the helmet and also to keep the air away from your face.  It does a great job for both of these problems.  It is easy to install and remove.  It simply tucks in to the appropriate slot on the helmet and that's all there is to it.  Once it is properly fitted, you will not have to worry about it falling out...It has a strong grip that keeps it from falling out.  If you did want to remove it, just grab it firmly and pull it out.  The Aero Skirt is one of most popular accessories for the Scorpion series helmets.  If you do not wear ear plugs, at least pick one of these up with your helmet.  It does a great job!