A little more expensive than some similar models, the SC9120B smoke and carbon monoxide alarm from BRK Electronics packs in loads of features into a single unit. The chief advantage is its dual functionality, eliminating the need to install separate CO and smoke detectors. The smoke detector relies on ionization technology -- often criticized for its beep-first-ask-questions-later "nuisance alarms"--, but uses a microprocessor to scrutinize readings before it sets off the alarm.

The other particularly nice feature is the battery backup. It's primarily a 120-volt wired unit, but the battery will keep it running for up to a month in case of power failure. The 9-volt battery is easy to access and change via a side-load drawer. This model also features a mounting system that's easy to install and a single button for testing or silencing the alarm. The SC9120B smoke and carbon monoxide alarm from BRK Electronics comes with a 5-year limited warranty.


Pros: Battery back-up
Cons: Price

Warranty
5 years, limited