ResoNix Foam Decoupler 2 is a 10mm thick closed cell foam (commonly referred to as CCF) and is used purely to decouple one panel from another, and features an automotive-grade adhesive to allow for an easy install. The purpose of this is to prevent audible rattles that are caused by two panels vibrating against each other. It works by providing a soft, compliant substrate for the panels to transfer their energy into instead of vibrating against another hard surface. The closed cell foam essentially provides a cushion of support between vibrating panels.
Closed cell foam should be used to eliminate panel on panel vibration noise in areas like doors/door panels, rear decks, and other various interior panels are the main offenders of a panel on panel vibration. When doing aftermarket speaker installs, constrained layer damping alone might not be enough to get the results you are looking for since it does not decouple panels.
We have designed our closed cell foam to have ideal properties to provide the best decoupling layer in the industry. We have found the perfect balance of providing a thick, yet soft enough material to decouple panels properly and is easy to work with due to its natural compliance.