Mass loaded vinyl is used as a septum material and also as a replacement for lead sheeting used with ITW's Muffl-Jac.

The mass loading of the vinyl provides a predictable blocking of sound passing through the vinyl sheet on the Muffl-Jac roll jacketing.  Vinyl is available in 1 and 2 pound per square foot density.  The degree of sound blockage is directly proportional to the density mass of the vinyl.  At one pound per square foot density, the vinyl will provide approximately 28dB noise reduction at 100 HZ; the noise reduction increases by approximately 6 dB for a doubling of mass/density, or for a doubling of frequency.