Propane Fridge Carbon Monoxide Alarm Battery Powered with Safety Shut-OffThe Unique Carbon Monoxide Alarm with Safety Shut Off is designed and CSA approved to Z21. 19 items unique to Canada for use with Unique propane refrigerators. With features like an integrated battery which is maintenance free for 7 years (no need to replace), improved sensor performance meaning less false alarms and more consistent performance and improved electronic performance in high humidity high temperature. Applications this truly is a new and