The digital superheat/Subcooling gauge saves high, low, and average values for detailed analysis. The pressures/ temperatures for R-22 and 31 other popular refrigerants are built in. Also included in this model is an A34000 access tee, a 6 foot (1.8 meter) dry/wet bulb, temperature sensor, five socks, and a protective carrying case. Low battery indicator alerts to replace the 9 volt battery (not included). Simple two button operation. Digital display with solid state circuitry automatically adjusts for fluctuating temperature. Sealed touch buttons protect against dirt and dust. One hour and 24 hour memory. Pulsation proof and accurate to any elevation up to 16,000 feet without adjustment. For use in most geographical applications. Pressure display range is 29 in. Hg to 600 PSIG (-98 KPA TO 4134 KPA). Temperature display range -40 degrees F to 200 degrees F (-40 degrees C TO 93 degrees C). Operating temperature 32 degrees F to 176 degrees F (0 degrees C to 80 degrees C). Maximum overpressure 800 PSIG (5512 KPA). 12 Month warranty. Made in the USA. For prior models that require a refrigerant multi key or specific refrigerant key, refrigerant keys are available. Please use A31992 as replacement 1/4" SAE cap.