Each R.F. shielded enclosure unless otherwise specified shall include a shielded window with a clear opening of 60 inches by 30 inches which shall include two layers of glass enclosing the copper screen shielding material within the dead air space created by the double glazed assembly. The glazing material shall be clear float glass 1/4 inch thick. The total window assembly shall maintain effective R.F. shielding equal to that of the shielded room. 2.5 HVAC R.F. SHIELDED PENETRATIONS AND SERVICES A minimum of one air inlet and one exhaust outlet of R.F. Shielded "honeycomb" shall be provided. These waveguide type air vent filters shall provide proper air passage for cooling, heating, and ventilation while also maintaining effective R.F. Shielding and equal to that of the shielded room. Collars and Nonconducting boots shall be supplied and installed to the parent ? ductwork. Likewise suitable collars and boots shall be furnished and installed to differs or grills in the suspended ceiling of the shielded room.