Excellent sensor with maximum sensitivity of 0.21oz/yr, the Freon leak detector detects all kinds of halogen refrigerants including but not limited to CFCs e.g. R11, R12, R13, R113, R114, R500, R502, R503 etc. HCFCs e.g. R22, R123, R124, R401A, R401B, R402A, R403B, R408A, R409A, R414B, R416A etc. HFCs e.g. R23, R134a, R404A, R407C, R410A, R417A, R422A, R422B, R422D, R507, R508B etc. Blends such as AZ-50. HP62. MP39 etc. 7 Adjustable Sensitivity, our refrigerant leak detector can be automatically adjusted to the best optimum detecting state. A flexible probe around 7.9-inch can reach to almost any awkward corners or space; More stable hvac leak detector with precise ultra-low power IC design Tricolor display of battery voltage; Siren sound and flashing light for the leak alarm indicator. Make sure to put 4 x AAA alkaline batteries in it.