We’ve had 3 of these smoke detectors go off for no reason after 18 months, who knows if these work when they are suppose to, ive braised meat in the kitchen that is no more than 8 ft from smoke detector and it has never alarmed! Why not? Packaging claims battery life is 10 yrs, this is second tome replacing, no more first alerts in our house! It goes off when on vacation and our dog is scared waits out side until the sitter shows up to dis alarm and throw it out in the garage and deactivate it. Don’t buy this brand choose another with 9volt battery when you change battery every year, we have better luck with those, MFG. Does not make it easy to replace.