Anyone used a HaulGauge weight gauge?

I recently stumbled across this product. It plugs in to the port onboard the truck and apparently can measure the weight of the trailer including the tongue weight, payload and weight distribution. Claims to be self calibrated by the truck model, you pull the trailer a short distance and it can give you all the weight ratings.

In theory if this thing works it would be very helpful, has anyone heard or used it before? I am skeptical that it works.

This thing looks really interesting, I wonder how it works, especially the tongue weight? I am not sure if I trust it or not.