Keep your family and home safe with this 3 unit package of X-Sense 10 Battery Combination Smoke and Carbon Monoxide Alarm Detectors with Large LCD Display (Standalone Model).Advantages include:2 in1 Protection - detects both smoke and carbon monoxide faster and more accurately than using a photoelectric smoke sensor and an electrochemical CO sensor10 year Battery Life - has a sealed lithium battery that provides 10 years of continuous power, saving you from changing batteries and power outages.Combination alarm with CO Readings: When the alarm is triggered, the LCD will display the CO concentration and illuminate.