The 294020 Shielded Nut Assembly is intended to provide RFI/EMI shielding on the inside of the housing.  Air which passes through the valve also passes through a 100 by 100 mesh Type 304 stainless steel cloth.  This cloth, when joined to the MIL-DTL-5541, Type 1, Class 3 conversion coated aluminum body with silver-filled conductive epoxy, forms a Faraday cage which protects the interior of the container from unwanted radio frequency and electromagnetic radiation.

The 294020 comes standard with a silicone base conductive gasket*, which is filled with silver-coated aluminum particles.  In order to make the conductive path complete, the interior surface of the case, which the conductive gasket touches, must also be conductive.