For pre-employment they aren't gonna watch you, but they may have you turn out pockets and you can't take in a purse or jacket. Mine is tomorrow and I plan on hiding it in my underwear between my thighs. Other people on Youtube/reddit have recommended in a pouch of briefs or in a bra if you have the anatomy that makes that practical. Your best bet is to put it someplace that seems comfortable and try walking around with it there, sitting with it, etc., just to make sure it's comfortable and isn't gonna show when you sit down/stand up/etc.

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For the container, QuickFix and any other reputable brand is gonna come with its own bottle with a heat strip on it, which is essential imo, otherwise you gotta carry a thermometer or find a temp strip and hope it's accurate and for the love of god don't get a thermometer that beeps.