Adjustment of sensitivity: Carefully the unit features 5 levels sensitivity adjustment, Slower and closer movement of the probe greatly improves the likelihood of finding a leak. When the gas leakage are discovered, Will hear "di di" sound . More refrigerant leak, more rapid, meanwhile the indicator light flash quickly. Upgraded: At each area checked, the probe should be moved around the location, at a rate no more than 25 to 50 mm/econd(1-2in/second). And no more than 5mm(1/4in) from the surface, completely around the position. When the leaked gas is detected, the audible tone will change to a "siren" type sound. More refrigerant, more siren. At the same time, Digital display screen display corresponding sensitivity quickly Easy set up: The leak detector features an automatic circuit and a reset function that set itself to ignore the ambient level of Halogen gas. Upon initial switch-on, keep in 6s and enter into the best state of detection. Widely use: It can detect all kinds of halogen refrigerants including HCs, HFOs, CFCs, HCFCs, HFCs and mixed refrigerants such as HVAC, R22, R410A, R134A, R1234yf ...It can be used for almost all air-conditioning refrigeration, including car and household air-conditioning and equipment refrigeration. The working temperatureis 0℃ - 52℃(30℉ to 125℉), Maximum sensitivity is 0.14oz/yr(halogen refrigerants). Electricity source need 6v DC, 4 x AAA batteries(not include). Colour:Red & Black Material:ABS Size:22.9 cm x 6.5 cm x 6.5 cm (9.01 x 2.56 x 2.56 inches),Fixed probe length:20cm (7.87 inches) Package Contents: 1 * Air Conditioning Refrigerant Leak Detector Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.