Check the listing for details. SILENT KNIGHT SD505-AIS : Ionization Smoke Detector. Condition: Used. Listed at 390.00 USD. * Devices were removed from a System working , ( in a Commercial/Office Building ) due to a FACP Upgrade. Excellent condition : No bumps ** functional / TesTed / The Smoke Chamber was blown out and cleaned * ** The SD505-AIS is effective in detecting rapidly burning fires with little smoke The Silent Knight SD505-AIS has responsive, yet high operational stability for an extremely wide range of uses. The SD505-AIS can be used in areas where early warning of trouble from super-heated or flaming combustibles is expected.The detector features automatic compensation for contamination and a simple detector sensitivity test procedure that can be run from the panel or remotely (using theSKSS 5660 or 5670 software with a Windows TM based computer)