transformer watt meter for 120 volts ac

Nice price. I installed one of these (well, it may have been a different "brand" but appears identical) and it works very nicely and appears to be accurate. It does appear to display actual power rather than apparent power...that is, the power (watts) is not always strictly equal to the product of the voltage and current.

I would suggest (and I myself did) putting a fuse in the voltage sense line just in case.