- Designed for applications where concentration of airborne particles is controlled such as pharmaceutical medical and other critical manufacturing environments.- Large rubber o-ring to seal the grille to the ceiling- Rubber washers for all mounting hardware- Apolycarbonate dust shield located between the speaker and the grille- Built-in amplifier- Capable of reproducing voice paging in clean room environments- Screwdriver adjustable volume control located on the 1 watt amplifier circuit board- 8-inch sp