My friends Works great and easy to use but when is got mine can't adjust voltage and current..

Great little device, and yes you can calibrate! No you do not hold both inputs in to go to calibration mode. Instead,
1) Go to the desired screen you wish to cal.
2) Push and hold the right input for 5 seconds. The screen will go dark. After 5 seconds, release.
3) Your voltages will now be flashing. Connect your meter to the desired location and press either the right button to increase measurement, or left button to decrease.
4) Once you are satisfied with the readout, press and hold the right input again for 5 seconds, then release. Your reading should now show what you changed it to.

Hope that helps everyon.

The first one sent to me didn't work. No matter how I tested it, I just couldn't "step down" the voltage or the current from the potentiometer. I tested out a few other things and nothing seemed to work. I received a replacement for the broken one through Amazon and this one works great. Amazon saves the day!

The board is good the case is a little chintzy but overall great product