MASTERCOOL 55900 Blue Refrigerant Leak Detector (IntellaSense II) "Super Sensitive Function" allows the unit further sensitizing beyond the standard settings for locating small leaks with gases such as R1234yf and R407C Intelligent tip design that senses the condition of the environment, to eliminate the potential of false alarms Detects all refrigerants (CFC's, HCFC's, & HFC's and blends) Flexible 15.5" probe for difficult to reach locations Sensing Element: Heated tin oxide