Today I am reviewing the GSD600 Gas Leak Detector from Amprobe. The GSD600 is designed to detect gases such as methane and propane gas with 35-ppm (propane) sensitivity. The GSD600 measures propane from 35 ppm to 580 ppm, and methane from 40 ppm to 640 ppm. The Amprobe GSD600 is fantastic for industrial, home, air-conditioning, and heating maintenance applications. It is ideal for checking gas pipelines, valves, regulators, and meters on gas equipment.