Today I used he probe sensor card to see the led readout. First I moisten my middle and index fingers by licking them. Next I put on rubber Crocs to ground the current. Then I turn the switch to on and the led readout switch to DOT. Then I place my two moistened fingers on the to leads coming off of the probe. When I move my fingers back and forth on the probes leads the LED readout goes up and down here is a picture of it.