I had one version/clone of the watts up, that also read low amperages accurately, I could discewrn No differences in the circuit boards or compnenets of it. I also destroyed one version when soldering the 8AWG to the shunt inside as I bridged the + and - and did not check it before plugging it in.
The next one I soldered I checked first, saw it too would have made the loud pop on hookup, and saw the solder bridge, and rectified the situation and as far as has been reported, is still working well.
I really like these little inline wattmeters, but I wish they would all read as low as 0.01 amp accurately, and would count higher than 64.9AH before flipping back to zero.
But they can be had for as low a 9.99$ on Ebay.