Extech 445580 Humidity and Temperature Pen, Fast Sensor, Dual LCD

I want to preface this review with the caveat that in order to achieve accurate relative humidity readings, this psychrometer will require the use of a 33% and 75% calibration salt kit. While they cost as much as this meter, they at least ensure accuracy, which was NOT achieved through factory calibration. As shown in the review image, the RH% reading is not calibrated we'll out of the box, but that can be expected as calibration can change in storage or shipping. I went through and returned several other psychrometers on Amazon before finally finding this one, which actually worked as described. The entire market is saturated with cheap Chinese clones where a company (sometimes reputable) slaps their name on, or changes the color of, the same generic Chinese psychrometer (often 12 degrees F or more off and unable to be calibrated). This meter, however, is unique in on the market and has the backing of the company that produced it. The calibration procedure with the Extech salt kit is easy. The meter is perfectly sized to fit within their calibration bottles and the directions are clear on how to calibrate both to 33% and 75% relative humidity. The construction of the meter exceed that of the competition as well. While It is still plastic, that plastic feels thicker and more solid than the other models on the market which feel like cheap toys. The meter reacts very quickly to changes in temperature and humidity, possibly sub-second, but does take a good 20 seconds or so to stabilize in a new environment. My goal for the meter was to establish as accurate a baseline reading for Temperature and Relative Humidity as possible for use in calibration many other sensors of varying makes and brands within my home automation system and I can gladly report that the goal has been achieved through this meter.

This is a a great device, I work for a mold remediation company and this is essential to our inspections. We get the temp and humidity reading within just a few seconds of turning it on and use the data between indoors and out to determine if there is a water intrusion issue. I does take about 10 seconds after turning on to deliver an accurate reading and is also best if not held in your hand when being used as it will cause a slight variance in the result.

Works as it should. Just as accurate as more expensive products

Purchased this device to calibrate a houseful of temperature and humidity sensors. Also purchased the calibration kit - which is as expensive as the device itself - to ensure a consistent implementation. Everything works as intended. I would give this 5 star except that it take up to 5 minutes to acclimate and stabilize readings when moving from room to room and especially between indoors and outdoors. Don't know if the more expensive devices like Fluke read faster, but it is simple enough to set this pen on a surface and come back in a few minutes for a reading.

Wanted a hygrometer that was accurate below 40% humidity. There are tons of cheap humidity meters on Amazon and EBAY some selling for $2 or less. They are completely inaccurate in dry weather. I live in a dry part of California and the humidity often drops below 20% and during a Santa Ana wind, can go to 5%. None of the cheap meters can measure dry air humidity, so don't waste your money on them, if you really want to know what is the humidity on a dry day.

Very accurate easy to use

Works well

I purchased this as an inexpensive tool to have for checking clients humidity levels in businesses. I found myself questioning its accuracy. The tool does not adjust as quickly as expected from exterior reading to inside reading. I’ve used extract in the past and I thought I was getting extract quality. I should have purchased their more expensive unit that I deem reliable.

Needs to be calibrated for the humidity reading.The calibration bottle cost a bomb,much more than the device itself.DO NOT BUY.Amazon and the seller were kind enough to arrange for a promt refund.One should buy only the thermomter....

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It does the job. 4 stars cause the price went up a lot.

Can someone tell me why this device can’t store temperature unit setting after switching? It always go back to default unit. The little button is very hard to press. Can you believe you have to do this every time you turn it on? Very annoying. You should close international port on Amazon if you only want to sell in US.

I just received the above product today. I have gone through the instructions on how to change from F to C which did work however it is already reading E2 error and needs to be recalibrated? According to the instructions this requires a salt reference bottle? Is this something that I now have to purchase? If so, we will likely return the unit. Please advise, thank you.