BRK SCO7B Smoke and Carbon Monoxide Combination Alarm with Voice and Photoelectric Photoelectric Smoke and Electrochemical CO Sensors Single button test/silence Exclusive! Voice alarm with programmable location. Programmable with up to eleven locations. Two silence features - can silence the low-battery chirp for up to eight hours or temporarily silence an unwanted nuisance alarm Optipath 360 TechnologyTM - patented technology provides 360 degrees of direct access to the smoke sensor. Perfect Mount - allows for easy alignment of alarm Spread Spectrum Horn Tone - Lower and varying frequency makes it easier for the elderly with normal aged related hearing loss to hear the horn Latching Features: Alarm Latch - remembers which unit initiated an alarm. Low Battery Latch: Visually indentifies unit in low battery condition. End of Life Signal provides audible notification alarms needs to be replaced 7-Years Limited Warranty