Device design and components:The data logger has a sturdy plastic shell around its electronic components.The preinstalled battery can be removed by opening its compartment using a coin.The cap covering the USB port has a good design. It can't be easily broken by twisting it or easily opened by accident, but still moves out of the way for plugging the USB in.The probe isn't detachable and can be submerged in water.This comes with a paper that lists warnings related to batteries and with a user manual, both of which are in English and Spanish.Recording temperatures:When moved to an area with a much higher or lower temperature, the logger takes much less time to adjust than either the digital or the mechanical room thermometer I tested it against -- around 10 minutes to decrease by about 60°F, and around 18 to increase that much.When it's recording and the screen isn't displaying anything, the blue "OK" light blinks every 10 seconds.It holds 3.3MB of data.Digital files:A pdf on the logger shows the product name, expiry date (2 years from the date it was produced and sent to me, though a sticker on the device itself says that it expires in 3 years), and recording accuracy. It asserts that the accuracy has been verified according to Texas Instruments' quality assurance program.The data report csv lists the serial number, stop mode and time zone used, date, time, and temperatures in both celsius and Fahrenheit.The data report pdf lists information on the device and its configuration (automatically set to a start delay of 30 minutes and a logging interval of 10 minutes).The pdf's data summary shows the temperature threshold (automatically set to 32°F - 86°F), the number of datapoints recorded, and highest, lowest, mean kinetic, and average temperatures recorded.The pdf's logging summary shows how many times the alarm went off due to high and to low temperatures and how long this went on.The pdf also has a nice graph of the temperature over time and a table of all recordings. These are both in Fahrenheit by default.Specialized software:Software to access more features is currently available on Windows, Mac OS 12.0 and up, as well as the Apple App store and the Google Play store.After installing and launching the Mac software App, it immediately indicated components were missing and automatically, without my permission, downloaded an additional software installation package named ToolServe.dmg which it then indicated was required to be installed to proceed. The package automatically downloaded from who knows where and the developer is unknown, so I didn't trust installing it and will not use it without finding more information. This additional required software is not mentioned anywhere on the Frigga website or in any of the manuals.The logged temperature data didn't show up in the software.The software shows the current device time, battery level, and some information that's also available in the pdfs.It lets you change the recording interval to 1, 2, 5, 10, 30, or 60 minutes. The start delay can be set anywhere from 0-1 days plus 0-23 hours plus 0-59 minutes. You can also set the time zone, enable or disable the stop button and multiple starts, and set the minimum and maximum temperatures with an accuracy of 1/10 of a degree Fahrenheit (and if you type in something outside the highest and lowest possible temperatures for this device, it will automatically correct those values). You can also import and export templates to easily switch between different sets of preset parameters.For those using the logger in the food and drug industry, the application includes an option to enable the FDA 21 CFR Part 11 module and an explanation of this.PROS:The device, its temperature recording, and the files it outputs all seem very good.Though this is a Chinese product, the English on the papers, files, and software is all easy to understand.CONS:I don't know how trustworthy the additional ToolServe software is.Though no special software is technically needed, this is misleading as it's the only way to change the preset parameters. If Frigga or its software ever stop existing, this device will only be useful in very restricted cases: logging temperatures between 32°F and 86°F every 10 minutes beginning 30 minutes after you turn on the logger, displaying temperatures only in in Fahrenheit, and only stopping recording by plugging in the USB.

TheFatRancher only reviews products he has actually used!The Fat Rancher installed a mini-split HVAC system in the garage this winter to combat freezing temperatures. A side benefit is having the garage cooled this summer. Sometimes too cool...The Fat Rancher is frugal, and is highly suspicious when he walks into the garage and it is more comfortable (cool) than the house. So when he saw the Frigga "M2E Reusable Temperature Data Logger with External Probe Multi-Use Digital Refrigerator Thermometer USB 14400 Points High Accuracy Temperature Recorder," he knew how to address his concerns.The data logger uses the free Frigga graphing software. Installation was a bit problematic, but progressed with no issue when installed with administrator level control on Win 11. Similarly, the software won't run except in administrator mode. Troublesome but manageable.The software works as it is supposed to, recognizing the USB data logger (albeit, a bit longer than expected) and loading the data into the graphing software. There are some idiosyncrasies with the software, such as having no daylight savings time settings. Also, the manual documents the settings, but not how the settings work. For instance, there are upper and lower alarm levels (which can't be turned off which seems short-sighted) and the data logger doesn't log unless these alarm levels are breached. This means that to measure the room temperature, I needed to set the alarm parameters outside of the temperature I intended to track. The instructions don't broach this operating necessity.The Fat Rancher is happy to report that while the mini-split was set for 80, the temperature of the garage only varied between 82 and 74 F. So, while not a very tight control band, not unusable. I'll reset the thermostat to 84 to minimize the energy use, except when I need to cool off.Overall a handy tool at a reasonable price.