This type of smoke and carbon monoxide detector uses electrochemical carbon monoxide sensors, which are currently the most accurate carbon monoxide sensors on the market. Compared to traditional electrochemical technology, the latter technology offers higher accuracy, lower power consumption, and a longer service life. The battery-operated smoke detector is suitable for indoor spaces such as villas, factories, shopping malls, warehouses, office buildings, etc. Feature - New 2-in-1 smoke and carbon monoxide detector. High-precision electrochemical sensor (the most accurate CO sensor). Infrared photosensor (the best sensor for smoke detection while minimizing false alarms) - Low power consumption design: After inserting 3 batteries (3 AA 1.5V batteries, batteries not included), you will hear the DI tone, and normal operation begins after 2 minutes. During operation, it does not display. Power-saving design. Long standby time and low power consumption. - Loud alarm: Press the "Test"