12 Pack, Plug In With Battery Back Up Carbon Monoxide Alarm, Contractor Pack, Utilizes An Electrochemical Carbon Monoxide Sensor To Accurately & Effectively Warn You Of Elevated Carbon Monoxide Levels, Can Be Continuously Monitored For Dangerous Carbon Monoxide Gas, Even During Power Outages, Simply Plug The Alarm Into A 120V Outlet & Personal Carbon Monoxide Detector Is Ready To Go, When Carbon Monoxide Levels Rise Above A Safe Threshold, A Loud 85 Decibel Alarm Alerts You To The Threat, Designed For Simple Use, Has Just 1 Button That Silences Or Tests The Unit, As Well As An End Of Life Timer That Lets You Know When It Is Time To Replace The Device, Open Stock TV #248-182, Brown Box Packaging.