18KHz. Operating Temperature: -20 to 50 ° C. Capacities: φ213 x 165mm. Network Wall Surface Mount Speaker GEN-6011A03 Power Supply: DC24V/1A or POE. Communication Protocol: TCP/IP, UDP, SIP, ONVIF. Signal-to-Noise Ratio: > 80dB. Frequency Feedback: 100Hz https://speakers42996.blogdun.com/30568598/just-how-an-ip-paging-system-improves-emergency-solution-in-workplaces