Safe-T-Alert Combo Carbon Monoxide Propane Alarm Surface Mount - Black [35-741-BL]Combo Carbon Monoxide Propane Alarm Surface Mount Black Have a safe TRIP! Test and inspect the Propane and CO alarms installed in your RV every week and replace malfunctioning alarms. Replace all Propane and CO alarms that are 5 years old or older. Install alarms listed for RV use. Prevent accidents by teaching family and friends about the operation of the alarms. Never ignore a sounding alarm. Features: Double duty alarm Detects both gas leaks and CO