When dangerous amounts of CO are detected, the CO1224T and CO1224TR CO detectors alert residents by sounding and flashing a temp 4-signal alarm. With 24/7 central-station monitoring, residents are guaranteed protection whether they are away from home, sleeping, or already suffering from the effects of CO. The CO1224T and CO1224TR CO detectors include RealTest® technology, so they can be tested using a CO gas agent, fully meeting the requirements of NFPA 720: 2009. To test, put the detector into RealTest mode, spray a small amount of CO into the detector per the installation instructions, and within seconds the detector will alarm, indicating successful gas entry. Designed for system operation, the detectors are fully listed to UL 2075 and offer a code-required trouble relay to send a sensor failure or end-of-life signal to the control panel and the central station.