moisture meter

Im looking at moisture meters and notice that there are some that do not start to detect moisture under 6%. Is there any required moisture percentage that needs to be identified?
The meters that I have found range
I have recently used a meter much like this one:
Analog Moisture Meter, Wood Moisture Content 10 To 28 Percent, Wood Moisture Content Accuracy Plus Or Minus 5 Percent, Cable Length 36 Inches.
When pressing the probes to you fingers moisture is indicated, and I applied a light mist to a wall and the meter detected moisture.