I have several of these now which I purchased from Gingerneil on here at a great price.
I use Brew Spy as well, which works well for me and is clear to understand.
I also don’t rely on them for exact gravity readings, but it’s great for a overview to identify when the gravity stops falling and fermentation is complete. The temperature reporting is good and is very useful for maintaining a stable brew fermentation and cold crash.
I pressure ferment so there will always be activities within the fermenter which will throw the gravity readings off by several points.