With its high flow rate, real-time ppm concentrations or TWA values are displayed instantly with corresponding audible tick-rate indicator to precisely pinpoint leaks. Rapid clearing time enables accurate ambient-air leak detection using the probe along a chiller or display-case. A re-zeroing algorithm and filter/bladder system allows the unit to be used in contaminated areas without affecting target gas readings. The rechargeable Li-ion battery provides a minimum of 8 hours of runtime for all-day usage.