The DeNova Detect DD623NCV is the first and only 10-year battery powered 2-in-1 Natural Gas + Carbon Monoxide alarm - no outlet and no wiring required. Engineered for faster, more reliable detection of natural gas and carbon monoxide leaks than conventional plug-in alarms, it is designed to be placed on the wall near the ceiling, where natural gas rises first to detect leaks sooner. Unlike 2-in-1 smoke/CO alarms, this alarm is purpose-built to detect methane (natural gas) and carbon monoxide leaks from stoves, dryers, furnaces, and water heaters - adding the missing layer of protection every home needs. Alarms should be placed in each room above natural gas appliances.