We have a similar fairy tale in Greece, about improving the MAINS bill on 220V.
Just few capacitors in a box with LED
too.
It called economizer ..bla bla bla .
The only logical interpretation is that it supposed to help the power factor of motors.
The point is that the households does not have large motors, and every device that it does need such capacitors,
the manufacturer have add them in it all ready.
Like air condition units , or small fan.
The electricians of Greece with their union had report this company to the Greek court of justice, but those cases takes years to clear up, and until them the scammer's will have make a small fortune.