The CD100A is designed to detect combustible gas leaks in residential and small commercial applications. Sensing leading combustible (Natural Gas, Propane, etc.), non-combustible and toxic gases and has <50 ppm methane sensitivity. Detects Propane-Based Refrigerants R290A and R600. Also known as “Natural Refrigerants” or “Not in Kind". Semiconductor sensor responds instantaneously to all combustible gases. The easily adjusted, steady tic rate provides a precise indication of the leak source. The CD100A can be used in tight quarters where others might not fit.