FAST Rings 6x9 Inch 3-Piece Car Speaker Enhancement Kit - Improve Sound Quality & Reduce Vibrations for Car Audio Systems

Great way to couple your speakers to the opening in your door. Makes a huge difference if you have a gap there. Speakers sound louder and much cleaner. Adhesive is actually very strong. Portion for the rear of the speaker directs the back waves into the large foam portion that helps absorb them. Sometimes the metal of your door can reflect these waves back through the speakers and make them sound muddy, echoing, or hollow. They work well in conjunction with dynamat.