Review on AMTAST Psychrometer Humidity Temperature Hygrometer by Tim Wheeler

I was just buying an old school hygrometer, a 3B Scientific U14293 from Revain when this came up on the 'you may be interested' list. While there weren't any customer reviews, I checked it out and found that the AMTAST HM550 is from a Chinese manufacturer with a bunch of other serious looking industrial sci-fi products. So I took a risk (having two hygrometers based on completely different technologies is fine with me). It was worth it. It came in a special foam-lined carrying case (not mentioned in the product listing). It comes with a detailed user manual, which is actually not necessary as the operation is quite intuitive. All readings I've checked so far, both relative humidity and temperature, agree with other instruments that I know and trust. For relative humidity, I also ran a 50% RH test (premixed chemical) and a 95% RH test (sponge in a closed container). When activated, the readings appear within a few seconds. I have found that the readings update every few seconds and stabilize to a more or less definitive reading within 30 seconds.