Both Mister Freeze Car AC Revitalizer and AC Pro uses r134a refrigerant. That’s about all that there is in common. The most important difference between Mister Freeze and other tools on the market is the ability to immediately measure the temperature of your A/C at the same time you are refilling the system. Mister Freeze uses patented AccuFill® technology which allows the system to sense the temperature that is coming out of your air conditioner at the exact moment you are refilling it. This helps you know exactly how much to recharge your system to get the exact temperature you would like. The digital display is easy to read and convenient to use and this makes our solution simple for anyone to use and recharge their A/C in minutes and get back to a cool, comfortable car.