Check the listing for details. Ajax HomeSiren-AJHS Wireless Internal Siren (White). Color: White, Condition: New. Listed at 93.79 USD. Wireless indoor siren. Sound power adjustable between 81 and 97 dB, white colour Sound alarm with customizable sound level between 81 and 97 dB. In open spaces it maintains communication with the Ajax Hub up to a distance of 2,000 meters Sound alarm volume: adjustable 81-97dB at the distance of 1 meter Operating frequency of piezo buzzer: 3.4±0.5kHz Indication of arm/disarm/armed status: Yes Power supply: from the built-in battery Battery type: 4 x CR123A battery, 3V Jeweler 868MHz communication protocol max distance between siren and Hub: up to 2,000 meters (in free area) Radio monitoring: Synchronization with the central unit every 12 – 300 seconds (customizable) Alarm activation time: less than 1 second Customizable alarm duration: from 3 seconds to 3 minutes Operating humidity: up to 7.