FSB (Flexible sound barrier) is a flexible, limp, mass loaded vinyl and is your how to solution for soundproofing interior walls and ceilings it has a acoustic rating of STC 26 (Sound transition coefficient) . FSB is an ultra thin, ultra dense sound barrier membrane designed to help deaden sound bleeding through common wall and common floor/ceiling assembly systems, it is also used to build enclosures for noisy machines like generators, compressors etc. Mass loaded vinyl helps create sound blocking assemblies to reduce airborne sound transmission for new or retrofit applications. These barriers are as heavy as lead but use no lead fillers. The density of FSB will impede your vibrations and lower the level of sound wave energy that is able to transfer through your common surface to the adjoining space you seek to protect. Use this product in both new or retrofit soundproofing construction.