It's an aircap. Really the heart of your spray gun. When you f up and drop your gun. It will land on the aircap every time, thus damaging the aircap It's the way the world works. The world likes to f with you. The aircap will never be the same after that. No matter how much you tweak the air horns around. For this you get rewarded by buying another one @ around $100 a pop.
Rating: [4 of 5 Stars!]