Safe Tech 2 in 1 Smoke and Carbon Monoxide Alarm - White

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, is 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.