I know CR123 is high performing, but I just can't carry a light where the only extra fuel I can scrounge will be on me. Wherever I go, CR123 is not commonly available in stores, and no others electronic equipment in my world uses that type of fuel. I don't view CR123 as being a practical choice of fuels for survival, but to each his own. Further, lithium AA is sufficiently high performing for my purposes.
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If you're reading this, it's too late.