Battery condition gauge

[Skyedriver]

A few weeks ago I saw a car with a little white gauge connected across the top of the battery. IIRC it gave a read out on battery condition etc but also acted like a tracker. Sure there was an App for the phone etc.
I know I'm not imagining this but cannot for the life of me remember it's name.
It wasn't expensive, made in China.
Anyone able to assist?
thanks

[E-bmw]

There are many different ones, I use these on each battery in the motorhome.

https://www.ebay.co.uk/itm/295644935211