The Kidde Front-Loading Smoke and Carbon Monoxide alarm offers protection from two hazards – fire and CO – in one unit. This 9-volt battery-powered alarm emits a beeping tone followed by a voice warning that clearly announces the danger by saying, "Fire! Fire!" or "Warning! Carbon Monoxide!" The uniquely designed front-loading battery compartment makes battery replacement quick and easy, and ensures proper installation. Manufactured with a photoelectric sensor for detecting smoke and fire, this alarm also includes the world's most accurate CO sensing technology based on claims by major manufacturers. The multi-function one button design includes: Hush® feature – temporarily silences nuisance alarms; test feature – simultaneously tests the unit's electronics and verifies proper operation; reset feature – resets the carbon monoxide alarm; alarm / peak level memory – if alarm has detected a CO level of 100ppm or higher since it was last reset, the green LED will blink once every 16 seconds and a voice alarm will announce "Carbon Monoxide Previously Detected" if the test / reset button is pressed; tamper resistant – deters removal of the unit from the wall or ceiling and optional battery carrier tamper resist feature that prevents the battery door from being opened; and cUL and CSA Listed.