Intelligent Ionization Technology - sensitive to fast flaming fires and other fires and reduces false alarms, Test/ reset button - test circuitry and resets alarm, A low battery chirp sound will warn you that it's time to change the battery, Talking Alarm - voice messages identify different dangers, a voice warning clearly alerts you if the unit has detected smoke, co or a low battery, Battery Powered - flexible installation for areas with no AC outlets, Hush Button - to quickly silence nuisance alarms -useful for silencing false alarms caused by cooking, steam, etc.