This is the first time seeing that.

So it gets base calibration data on running around empty then shows me what it thinks I have in weight after I hookup and run aruond for a while?

Seems neat but error prone.

They also make tow balls with integrated scales but I don't think it will fit in my WDH hitch. Honestly measuring my tongue weight does me no good with my setup, as I don't have room to move anything around. Best I can do is just not fill up the fuel jugs until right before my destination. Hard to do when I get such a good price on 93 here next to the house vs up north/west away from the refineries.