I have the identical one in my tower - its comes with select Coolermaster PSU's. I have the 450W realpower. It connects to some wierd connector on the PSU - I pretty sure you can only use one if you have a Coolermaster PSU.
Its a real-time wattage reader, but I doubt the accuracy is very good - It says my system (in sig) at load is only pulling 150-200 Watts!?!
Can anybody verify how accurate this may be?