The life expectancy of smoke alarms is generally 10-years, after which point their sensors can begin to lose sensitivity. The test button only confirms that the battery, electronics, and alert system are working; it doesn't mean that the smoke sensor is working.May 2014 issue of Consumer Reports
Interconnected Smoke/Carbon Monoxide Detectors
Wired Interconnect or Interconnect using Wireless Units
If one alarm goes off (at the other end of the house) they all go off2.
10 Year Sealed Lithium Battery Alarms
If your existing alarms are already interconnected these units will eliminate the need to change the battery every year
Combination Smoke & Carbon Monoxide
Children are curious. They crawl, they feel, they touch, they explore. But sometimes curiosity can lead to danger, such as when children tamper with an electrical receptacle. Fortunately there's now a receptacle that can safeguard this everyday source of danger. Learn more about Tamper Resistant Receptacles (TRRs) and their life-saving potential.