Tracer Spectronics Corp TP-9360 PRO-Alert Electronic Refrigerant Leak Detector Optimum sensitivity detects leaks of 003 to 006 oz/year Automatically self-calibrates to neutralize background contamination Sensor life up to 200 hours or more Sensitive to both R-12 and R-134a refrigerants Certified to meet SAE J1627 High/low switch for accurate diagnosis of both large and small leaks