I just ordered one from ebay.
I note that there is more info from https://www.navitron.org.uk/forum/index ... 68.75.html
One of the guys there proves that it uses 433mhz and links to https://www.en4rab.co.uk/onzo/
which has some onzo downloads.
I think they are for windows not linux
I bought one of the efegy ones from Maplin £20 and I find it great as it has a phone app and shows historic usage just didnt get the display. So I will be using Onzo for display only.
I also use the Welsh company https://emoncms.org
arduino shield £14 which I find successful and updates to their interface.
On another property I used Arduino+ethernet shield and 33ohm resistors +10 x Current Transformers www.tme.eu/en/details/az-1000/current-t ... rs/talema/
. This also connects to the welsh lads and works fine for the last 6 months
To the best of my knowledge https://openenergymonitor.org/
have pi software