 So if somebody wants to go in and buy a can of Freon or 134, how do they know if it's real? How do you know what's in the can? You don't want to buy the stuff from the sealer. If you read the can and it says pure HFC 134A refrigerant with no additives, you're good. If any can says anything other than that and it's got additives and special oil or sealers or whatever they brag about on their label...