First Alert CO605 Plug-in Carbon Monoxide Alarm vs First Alert SMCO100 / SMCO200V Combo

Side-by-side specs from each maker.

Only the differences are shown.

First Alert CO605 Plug-in Carbon Monoxide AlarmFirst Alert SMCO100 / SMCO200V Combo
TypeSmoke or CO alarmSmoke or CO alarm
AlarmCOcombo
SensorelectrochemicalPhotoelectric (smoke) and electrochemica
PowerPlug-in with battery backupAA (2 alkaline, replaceable)
Replace afterNot listed10 years

First Alert CO605 Plug-in Carbon Monoxide Alarm

A plug-in carbon monoxide alarm with an electrochemical sensor, battery backup for power outages and a single test and silence button.

  • Battery backup
  • Plugs into a standard outlet
  • 85 decibel alarm
  • Needs an outlet

First Alert SMCO100 / SMCO200V Combo

A battery-powered smoke and CO combo alarm that runs on two replaceable AA batteries. The maker says the unit itself should be replaced at least every 10 years.

  • Replaceable AA batteries
  • The maker lists a replacement interval of at least every 10 years