PROV. When there are no PROV sets to try, I found that most of the time CAFL or XTRA (which tends to be CAFL with extra frequencies added from research done later) work great and more often than HC or KHZ.
However, when CAFL or XTRA tend to not resonate with an issue, sometimes you will find that the HC or KHZ sets do.
HC probably is more preferred over KHZ given the source of the frequencies.
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