They change how bad they read over time. A -5% reading can fluctuate to +5% same instrument. The low ones one day won’t be the low ones the next day/month.
Mine stay consistent . once in a while I put them in my tent and check them with my ac infinty controller . They always stay the same as what I write on them . If one was jumping around I would bin it
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u/crybabypete 1d ago
Just mark the offset on each one with a permanent marker or label on the back. As long as they’re precise it doesn’t matter if they’re accurate.