It is a fully supervised wireless siren, for indoor use. Siren Type: Piezo, 109dB SPL @ 1m, 1.8-3.5 kHz, sweep frequency 7Hz, Internal Battery: 3.6V 13Ah non-rechargeable EVE Lithium battery, EEMB type ER34615M, Battery life expectancy: 3 years (for typical use), Operating Frequency (MHz): 315, 433.92, 868.95, or other frequency according to the requirement in the country of use, Receiver and Transmitter ID Type: 24-bit, Flash Lights Duration: 100ms ON, 900ms OFF, Dimensions (LxWxD): 161x161x50mm, Weight (with battery): 470g , Color: white, Operating Temperature: -10°C to 60°C, Compliance with Standards: EN 50131-1, EN 50131-4 Grade 2 Class II, Swedish SSF 1014:3, Belgium TO14A. The MCS 720 has been tested and certified to EN 50131-4, EN50131-1 for security Grade 2, environmental Class 2.