2-in-1 Highly Sensitive Alarm: Combination smoke alarm and carbon monoxide alarm has a built-in intelligent chipset. The photoelectric smoke sensor and electrochemical CO sensor with the Intelligent Real-time Monitoring System complies with UL 217 and UL 2034 standards, which ensures the highest level of safety and reliability. The highly Sensitive 2-in-1 co and smoke alarm combo is accurate and reliable, suitable for house, bedroom, living room, garage, hotel, indoor, vehicles, factory..LCD Display:The smoke carbon monoxide alarm combo's LCD digit indicates real-time carbon monoxide (CO) concentration in the surrounding air, as well as the battery levels. A low battery warning （“LB”）lets you know it is time to change the battery; a smoke warning (“HHH”) lets you know that a smoke fire is happening..Three Alarm Mode: 85dB Buzzer & LED & Human Voice Warning. The 85dB loud buzzer with rapid flashing red indicator light will warn you when dangerous smoke or CO concentration is detected. The smoke alarm carbon monoxide alarm will emit clearly human voice warning to warn the kids and the oldster to escape the dangerous..Auto-Check System: This 2 in 1 smoke alarm and carbon monoxide detector has the Auto-Check System. The system will real-time check sensors, green light indicates function properly; yellow light alarm for equipment fault, enables you to know the running status clearly..Simple to Use & Easy Installation: The test/silence button operation of this smoke carbon monoxide alarm enables you to test the alarm weekly, easily silence when false alarms. Battery powered 2-in-1 carbon monoxide fire alarm with the included screws, anchor plugs ,requires no rewiring, easy to mount on any wall or ceiling.