lacks documentation and not as plug-n-play as advertised but with a little fiddling, it does what it's supposed to.

Note:
1. If the module can not be adjusted, the output voltage is always equal to the input voltage." When you encounter this problem, please counterclockwise rotation of the potentiometer 10 laps or more, then you can adjust the output voltage. Because the factory default output voltage is 17V.
2.Module output terminal string has a current sampling resistor, there will be 0-0.2V voltage drop after connected to the load, it is a normal phenomenon.
3.If its output is more than 3A/35W, please enhance heat dissipation!

4.This DC converter is single output, the output voltage of the USB port is the same as the output voltage of the module, if your load is USB device, please make sure the module's output voltage is set at 5V. "

Working well with no issues so far. Using mine to convert a 12 volt supply down to 5.1 volts to power a rasberry pi which will control an LCD panel (also running off the 12 volt supply).
I did notice that it took quite a few turns (counter clockwise) before the output dropped down from 12v,
Also - the Amazon picture on close inspection, shows the top and bottom clear pieces of the case reversed... the piece with the holes go on top.

Great products does exactly what it says

Will definitely buy again

Great toy for the nerd.

Part as expected and sent efficiently.