Both the ASYRA and the ZYTO have the capability to do three things simultaneously:
They output tiny electrical currents between what’s known as the EAV (Electro-Acupuncture-Voll) points on your fingers, they measure the amount of electrical resistance or impedance between these points on the fingers and establish a baseline, and finally, the hardware outputs various frequencies and measures changes in the above mentioned electrical resistance in response to those frequencies.