Hi @ mrposyble, very modern and useful hunting.
Most people live under some sort of stress, so that this device will come for many people well.
His work has come from with scientific work and experiments with people exposed to some type of stress and improvements related to the use of Doppel.
The mode of operation that, Doppel gives rhythm (vibration) on our wrists in accordance with the rhythm of our heart is very logical.
Doppel works like music in the mood but Doppel work does is discreetly and quietly.
Less stress is greater focus, which is equally clear because these two phenomena are inversely proportional.
It makes sense, it should be tried in a real (stressful) life.

Good luck with hunting.