Check the listing for details. First Alert, BRK, SCO2B CARBON MONOXIDE & SMOKE ALARM COMBO DETECTOR (6 PACK). Condition: New. Listed at 269.85 USD. Separate smoke and co detects both dangers and eliminates the need for two separate alarmsElectrochemical co sensor is the most accurate technology availableLatching alarm indicator remembers which unit initiated an alarmSeparate Smoke and CO detects both dangers and eliminates the need for two separate alarmsElectrochemical CO Sensor is the most accurate technology availableLatching Alarm Indicator Remembers Which Unit Initiated an AlarmEnd of Life Signal Provides Audible Notice When Alarm Needs to be ReplacedTwo Locking Features Pins Lock Battery Drawer and/or Alarm to BaseSeparate Smoke and CO detects both dangers and eliminates the need for two separate alarmsElectrochemical CO Sensor is the most accurate technology availableLatching Alarm Indicator Remembers Which Unit Initiated an AlarmEnd of Life Signal Provides Audible Notice When Alarm Needs to be ReplacedTwo Locking Features Pins Lock Battery Drawer and/or Alarm to Base