Gascheck G3 Handheld Leak DetectorAccurate Reading Calibrated for helium, the unit also has multiple gas selection including Ammonia, Argon, Butane, Hydrogen, SF6 and some refrigerants. When searching for leaks the unit can easily be set into auto range, giving the maximum sensitivity when required. The GasCheck uses a robust micro thermal conductivity sensor to detect any gas providing it is different from air or nitrogen.