[CO and Smoke Combo Detector] With advanced electrochemical carbon monoxide sensor and photoelectric sensor, CO and smoke detection is accurate. [Flashing and Loud Alarm Pattern Warning] When dangerous smoke or CO concentration is detected, it will warn you with LED flashes and loud alarm sound. [LED Display Screen] Can clearly indicate the real-time carbon monoxide concentration in the surrounding air. [Battery Power Supply] Powered by by 2 * AAA (not included), no need to charge, no messy wires, convenient to use. [Easy to Install] Comes with a bag of screws, easy to install the detector on the walls of bedroom, living room, kitchen, etc.