What is a key feature to look for when purchasing a smoke detector?

A key feature to look for when purchasing a smoke detector is battery backup. This is essential because it ensures that the smoke detector remains operational during power outages, which can happen at any time due to storms or other emergencies. A smoke detector without battery backup may not function during such critical times, putting individuals at increased risk.

Having a reliable power source is vital for the effectiveness of smoke detectors in alerting residents to potential fires, thus enhancing safety. In addition to battery backup, other features, while they may offer convenience or additional functions, do not necessarily provide the fundamental assurance of continuous operation during a power failure.