Model QS408 is a welded steel protective enclosure having a volume of 1 cu. ft. (.028m3). The interior is undercoated to eliminate metallic resonance and is furnished with 11/2" (38mm) thick fiberglass with a 11/2 lb./cu. ft. density. The large volume of this enclosure improves the low frequency response of the system while the fiberglass controls undesirable resonances in the high end of the frequency spectrum.