Smoke & Carbon Monoxide Combination Alarm, 10 Year Tamper Proof Battery with Flash

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 with DC 3V built-in lithium battery with 10 years battery life, not hard-wired or mains powered detector, convenient to install, save the 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 ba...