The Macurco GD-2B is a low voltage electronic detector of combustible, heating type gases. The GD-2B is designed for connection to Fire Alarm/Burglary Control Panels. The GD-2B is intended for installation in buildings in non-hazardous locations such as residences, retail stores, office buildings, and institutional buildings. This combustible gas detector has been designed to detect methane (natural gas) and propane (LP) gas. It is NOT designed to detect smoke, fire or carbon monoxide. The GD-2B is a low voltage (9-32VDC, 12-24VAC) electronic detector of combustible, heating type gases, that has been calibrated for methane (natural gas) and propane (LP) gas. The GD-2B is designed for connection to Fire Alarm/Burglary Control Panels. The GD-2B has a SPST Alarm relay, for connection to control panels or other devices. The GD-2B does NOT detect carbon monoxide. The GD-2B has an optional internal audible sounder.