The SAFE-T-ALERT 70 Series combination CO/Gas Alarm is an alarm that combines into a single compact system, a powerful alarm that detects both Carbon Monoxide (CO) and explosive gases Propane (LPG) and Methane(Natural Gas). The 70 Series uses the latest microprocessor technology combined with two electronic self-cleaning sensors that operate independently of each other. The combined unit can detect both CO and explosive gases simultaneously. This detector is UL Listed as a CO Propane and Methane (Natural Gas)detector for RV use.