Ceiling speaker with sealed rear chamber and high molecular substance speaker vibration section to prevent floating dust particles from contaminating medical, chemical or IC/photo film productions. Suitable for clean rooms, hospitals and laboratory applications. Temperature range from -20 ° to + 55 °. 5 W RMS Power in 100 V line. 8 cm speaker. Frequency response from 150 to 20,000 Hz. Sensitivity 87 dB at 1 W, 1 m and 1 kHz. Diameter of grille: 116 mm. Depth: 110 mm. Embedded hole: 98 mm. Weight: 620 g.