Check the listing for details. Mastercool 55900-COMBOKIT Electronic Leak Detector Combo Kit. Condition: New. Listed at 399.99 USD. This kit includes: 55900 and 89661-AYF55900 FEATURES/SPECIFICATIONSMeets and exceeds J2791 (R134a), J2913 (R1234yf) and EN 14624 At the heart of this leak detector is a new low power metal oxide gas sensor with superior performance properties such as lower current consumption and sensor longevity.The sensor is characterized by high sensitivity and fast response upon detecting the presence of extremely small levels of chlorofluorocarbon gases.Powerful microprocessor was integrated into the design that automatically selects the best operating condition for the sensor to ensure optimum performance throughout the life of the sensor.89661-AYF FEATURES/SPECIFICATIONSProfessional extruded aluminum block2-1/2" silicone dampened, recalibrateable gaugesFree-floating piston type valves reduce o-ring wearExtra access port for vacuum lineExtra large sight glass for visual refrigerant checkLarge easy-to-grip knobsR1234yf high and low side couplersR134a high and low side manual couplersAdapters3-60" R134a standard hoses