LP Gas and Carbon Monoxide Combo Detector - Why have 2 separate alarms when you can have just 1, this single unit detects both LP and CO gases! Hardwired in and uses chassis and battery power to help protect your family. This alarm has 6 different modes - Power off Mode: Visually indicates sufficient and insufficient power to the alarm. Gas Sensing Mode: Continually monitors gas concentrations to ensure they are at acceptable levels. Alarm Active Mode: Indicates that one or more gas concentrations have reached unsafe levels. Visually and audibly alarms to alert to potential dangerous situation. Alarm Test Mode: Visually and audibly verifies proper alarm operation. Alarm Reset/Stabilization Mode: Silences audio alarm for 6 minutes. Verifies proper alarm operation. If gas concentrations are still high after the six minutes the alarm will sound once again. Fault Mode: Indicates a fault has been detected that compromises the alarm. ETL listed and tested to UL 2034, UL 1484 and CSA 6.19.00 for RV applications. Dimensions: 3.44 inch W x 3.56 inch H. 1 per package.