Instruct: Classify the given review into positive or negative sentiment.
Query: No more

I have no faith in these anymore. Some have calibration screws, some don't. Some have the same results with the digital hygrometers that have been humidity tested but just as many have varying differences. Even the one's that do have the cal. screws don't seem to keep consistent with humidity changes. It would help if the manufacturers either:1. Provided instructions for these things.2. Made a consistently quality-sure product.Mercy!