So here's the deal: the unit is nice and seems to be calibrated relatively well. The literature that comes with it says it has +/- 10% error window. This perhaps seems extreme, but we have to remember this is a consumer unit and the professional models are an order of magnitude more expensive. For my part, I'm satisfied with the accuracy because the readings I'm getting are almost identical to those of a professional home inspection company. The alarm does function well; ours has gone off at least twice in the last week (we are seeking remediation) and I've been able to hear it upstairs although it doesn't strike me as obnoxiously loud as a fire alarm. But you do still hear it. Now my MAJOR quibble with this unit: it will chart all the data points and show you your history and median and peak values. Great. But it does not chart this data relative to TIME. In other words, you can export 200 readings and they will just be 1, 2, 3, 4,...200 etc. The radon in my home cycles. There's a peak and trough every day and the pattern repeats itself daily. What time of day did it peak 4.71 and again a day later 4.2? I have NO IDEA. I just see a peak, but I don't know the date or the time. This strikes me as unbelievably dumb, for a unit that is bluetooth connected, has a color screen, and can communicate with an app on my phone. You mean to tell me it can't also log the date/time of each reading? a couple bytes of text data? You've got to be freaking kidding me. I've sent a message to the developers and I realllly hope they update the firmware/app to accommodate this function. It is such a glaring omission I cannot believe it made it to market without it. I would send it back for this reason alone if it weren't for the fact that a.) it seems to be giving me accurate readings and b.) it's a bit of hassle for me to ship it back at this point and c.)similar units with fancier apps have a fair number of bad reviews with people complaining they are not accurate. I'm still peeved though.

I own 3 Radon monitors. The RadonEye, an Airthings Wave (2nd gen), and Corentium Home (also by Airthings). The Airthings monitors have had questionable accuracy over the past 11 months. The RadonEye has been much more accurate when comparing all 3 monitors to charcoal test results. That said, the most important thing about a Radon monitor is accuracy. I recommend this product based on accuracy alone. Additionally, I like that I can get a quick reading by looking at the small display on the device. The bluetooth sync functionality actually works fine between floors/walls, so lack of wifi connectivity hasn't been a problem. I love that you get your first accurate reading after only 1 hour with this monitor. The Airthings Wave takes a whole week to calibrate and they say to let it run for at least 30+ days to consider the readings accurate. I dock 1 star from the RadonEye for the following reasons though: - The app seems outdated aesthetically. When compared to the Airthings app and web dashboard it leaves a bit to be desired. - Learning how the RadonEye takes measurements can be a little confusing at first. It takes a reading every 10 minutes and then spits out an avg every hour. In the app these are called "data points" and graphed out as pci/l on the y axis and # data points on the x axis. I wish this graph was more of a time based graph, rather than showing how many data points you have and requiring you to do your own math to figure how long the monitor has been measuring, or the time a reading was taken based on those data points. - This isn't a very attractive device. Just a white cylinder with a screen on it. - I wish this had a longer power cable, or was battery operated. Being tethered to a wall socket limits the positioning of the monitor. Overall, despite my issues with the RadonEye, it's all about the accuracy in the end, and this thing has it. I recommend this product if you're in the market for a "smart" Radon monitor.

Update (08/20/2020): There is a new app now available which is much better than the prior version. The old app didn't auto update to the new app. One has to download the new app and delete the old one. The new app is lot better with ability to delete a saved data file, uses the full screen space, has ability to zoom in on the data etc. There could be lot more things one can add and make it better but I am happy with what they have done with the app. So, raising to four star from my original three start rating. Original Review: The Radon Detector seems to work fine. It detected high Radon levels in my basement and I ended up converting the passive venting system to an active venting system by installing a radon always on fan. The detector showed that the radon level dropped to an average of 2pCi/l from above 4pCi/l. The biggest complaint I have with this radon detector is the iPhone application. Firstly, you do need the application as there is only limited information on the Radon Detector screen itself. If you want to look at history of the readings or change any settings etc. then the app is a must. The application has very limited functionality and lacks basic features. For ex, if you accidentally save a chart you can never delete it. The app is not even optimized for the taller iPhone X screen and it looks archaic. There is no way to zoom into the chart or check any specific data point until and unless you download the data in excel. And yes, the app does allow data download to excel once you save a file within the app. The last update for this app was 9 months ago and that makes me wonder if the company has already dropped support. Once the app stops functions this Radon Detector would be quite useless as the application provides the only way to change setting and extract data for this detector. Another annoying part is that the app description in the Apple app store is all written in Chinese (or a similar script). Thank god at least the app itself is in English! I understand the need for multiple languages but at least English should be there.

Initial impressions going on 3 days use: Came packaged like an apple product - nice. Set up was a breeze. Plugged it and, then downloaded app and one tap connect by blue tooth. First reading in about 10 minutes. Works as advertised. The app is simple, allows you to switch between units, adjust alarm (on/off, alarm value, and interval). Main page shows current reading, day average, and month average. Plus current measurement duration. Will update later. Concerns so far: 1. Quick set up instructions were clear. English user manual was not - i am guessing it was written by a Korean with english as a distant second language. 2. Documentation states the sensor calibration is only good for 2 years. Nothing in the documentation about what to do after 2 years - recalibrate or throw it away? 3. App - Main page of app has a lot of unused real estate - which is frustrating since much of the info displayed is in very small font (other than current reading). Would love it if they would increase the font and clearly display all info. You can see a graph of data, but no way to share the data except through itunes. 4. Unit - only complaint so far is that it needs to be plugged into an outlet. I'd prefer battery power to make it easier to place this where i want and in case of power outages. All in all, happy with purchase so far.

Without another accurate Radon detector with which to compare, it’s hard to tell how accurate this one is but the readings have been consistent since it was activated and it makes sense that the average is in the low 1’s in a newly constructed home built with radon barrier/exhaust. This device gets high marks for being easy to read and understand as well as being able to access it on the iPhone and iPad. I rated down one star on ease of use since the included instructions were unclear about which app to download for use - the third one I tried “RadonEye” (not Plus) was the correct version and it worked instantly once I used that.