Product review (5 stars): I'm not a professional, but I've found it useful and easy to use
I'm not a HVAC professional, but I am a scientifically-minded home owner. I've been curious as to how different actions affect the humidity in our pool room, among other things. I have no idea if this meter is correctly calibrated or not, and the manual doesn't talk about how to check this or calibrate it. However, I strongly suspect this is more accurate than anything I currently have. I mainly used the meter to check how an action changed the humidity or temperature in a room, which it appeared to do just fine.

"The meter displays three different temperature points of the air surrounding the meter's sensor: ambient, wet bulb, and dew point." The meter has buttons that allow you to hold, save, and/or recall data. It also has a MIN MAX AVG function. The directions are brief but I was able to use all these functions without a problem. The meter is powered by 4 AAA batteries. There is a power on/off button, but the meter will also automatically turn off after 20 minutes. There is a button to turn on and off a display backlight. The meter has a belt clip.

The display was large enough to read easily. It quickly arrived at the reading (about 3-5 seconds to stabilize unless in an area of air movement). The meter is for indoor use only. The manual warns "To extend sensor life, keep the sensor's protective shutter closed whenever the meter is not in use." There are no further directions about this shutter, but I can't find one despite the picture. It's possible I'm overlooking the obvious, but perhaps the obvious is that there isn't one.

I'd recommend reading the reviews by professionals. From the description I read to decide to review this or not, I'd assumed it was around $75 and "of professional quality" rather than an actual professional meter. I'd normally have left this to in-that-profession reviewers as I have no way to compare this to similar meters on the market nor can I comment on if the pricing is reasonable. I apologize for that lack in my review.