How are you going to know to call the mitigator for a warranty repair? What is a warranty worth if there is no reliable and easily-recognized warning of system failure during the warranty period? Fast, Accurate results on a digital display for both short term and long term radon monitoring and record keeping. This instrument delivers an audible warning if the fresh air/radon mitigation fails or declines in performance. An audible warning is especially important to give value to a radon mitigation warranty. Compare with the silent and usually concealed blue or red oil-filled U-tube manometer that is almost always in an out of sight location, usually at the far end of a closet and out of sight.