I have this tool, used in another vehicle. Here's what good about it:
Always quickly reconnects to your bluetooth. Unlike cheaply manufactured bluetooth devices which have memory leaks and 'freeze up' after being powered for over a day, this one has no problems.
App has special menus to perform voltage drop checks when cranking.
Automatically sends periodic notifications of battery life.
The displayed voltage is just as accurate as some of the best meters.
Useful when playing music from the radio without the engine on - determine a good time to restart the car to charge the battery.

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2003 4.6, esotril blue, over 215,000KM. Every previous owner failed to keep up the vehicle maintenance. Restoration project.