2 in 1 Smoke & Carbon Monoxide Alarm, Combination Smoke Detector with Flash， 10 Year Tamper-Proof Battery

2 In 1 Combination Smoke and Carbon Monoxide alarm, can detect both smoke and carbon monoxide, it combines smoke and carbon monoxide dual sensors in one detector, which will reduce the cost.Also, it has DC 3V built-in lithium battery with 10 years battery life, not hard-wired or mains powered detector, convenient to install, saves battery cost. Large test button for easy recommended monthly testing, when you want to test the device, no need to take it off, just need a rod or a stick to press it. Low battery warning. 10 Year Product End-of-Service Life Warning. Figaro CO sensor from Japan, which lasts for 10 years. ETL certification with UL 217/UL 2034 test standard.