Low Frequency Sounder notification appliances meet the NFPA 72® 2010/2013 low frequency requirements for all commercial and certain residential sleeping spaces. The Sounders provide Temp 3, Coded, Continuous, and now provide Temp 4 which meet the NFPA 72® 2010/2013 low frequency requirements as well as the NFPA 720® 2012 carbon monoxide low frequency requirements. Studies driving these requirements have shown that a lower frequency is more effective at waking individuals in a fire event, including those with mild to severe hearing loss.