This is the one to buy - the other from Derale which has a radiator probe that goes into the ribs isn't as good. Buy this one because you can thread it straight into the water channel and get a direct reading. Has been working great for a few months now and will definitely buy again. I'm using it with a non-Derale fan, so no problem there either. The maximum fan current is 25A, which should be enough for most 16" fans.