RV LP Propane Gas Detector with CO Carbon Monoxide Alarm - YouTube
Kidde Nighthawk Carbon Monoxide Detector & Propane, Natural & Explosive Gas Detector, AC-Plug-in with Battery Backup, Digital Display, White & Smoke Detector, Battery Powered with Test Button - Amazon.com
Digital triple gas detector (CO, natural, and propane) 120 V & 9 V.