Protect yourself, your family, and friends from carbon monoxide poisoning plus propane and natural gas leaks with this combination detector/alarm. The alarm plugs into standard household electrical outlets and is equipped with a 9-volt battery back up for continued protection during power outages. A Peak Level Button lets you see the peak CO level recorded by the gas alarm since it was last reset or unplugged. A continuous digital display shows carbon monoxide levels, and a co detector natural gas (methane) or propane with the display showing whether an is present.